Phenotypic Mutation 'bullet_gray' (pdf version)
Allelebullet_gray
Mutation Type critical splice donor site (1 bp from exon)
Chromosome13
Coordinate94,587,594 bp (GRCm39)
Base Change G ⇒ T (forward strand)
Gene Ap3b1
Gene Name adaptor-related protein complex 3, beta 1 subunit
Synonym(s) AP-3, Hps2, beta3A, rim2, recombination induced mutation 2
Chromosomal Location 94,495,468-94,702,825 bp (+) (GRCm39)
MGI Phenotype FUNCTION: [Summary is not available for the mouse gene. This summary is for the human ortholog.] This gene encodes a protein that may play a role in organelle biogenesis associated with melanosomes, platelet dense granules, and lysosomes. The encoded protein is part of the heterotetrameric AP-3 protein complex which interacts with the scaffolding protein clathrin. Mutations in this gene are associated with Hermansky-Pudlak syndrome type 2. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Nov 2012]
PHENOTYPE: Homozygous mutants exhibit hypopigmentation, elevated kidney levels of lysosomal enzymes, platelet storage pool deficiency, reduced ipsilateral projections from the retina to brain, reduced sensitivity of dark-adapted retina and shortened life span. [provided by MGI curators]
Accession Number

NCBI RefSeq: NM_009680; MGI: 1333879

MappedYes 
Amino Acid Change
Institutional SourceBeutler Lab
Gene Model not available
AlphaFold Q9Z1T1
SMART Domains Protein: ENSMUSP00000022196
Gene: ENSMUSG00000021686

DomainStartEndE-ValueType
low complexity region 10 24 N/A INTRINSIC
Pfam:Adaptin_N 39 586 1.2e-170 PFAM
Pfam:SEEEED 672 812 1.3e-27 PFAM
AP3B1_C 822 969 1.58e-78 SMART
Blast:B2 993 1103 2e-27 BLAST
Predicted Effect probably benign
Meta Mutation Damage Score Not available question?
Is this an essential gene? Possibly nonessential (E-score: 0.320) question?
Phenotypic Category Autosomal Recessive
Candidate Explorer Status loading ...
Single pedigree
Linkage Analysis Data
Penetrance 100% 
Alleles Listed at MGI

All alleles(51) : Targeted, knock-out(1) Targeted, other(3) Gene trapped(32) Spontaneous(14) Chemically induced(1)

Lab Alleles
AlleleSourceChrCoordTypePredicted EffectPPH Score
IGL00660:Ap3b1 APN 13 94527371 missense probably damaging 1.00
IGL00766:Ap3b1 APN 13 94679392 splice site probably benign
IGL01784:Ap3b1 APN 13 94630247 missense probably damaging 1.00
IGL01979:Ap3b1 APN 13 94584971 nonsense probably null
IGL02040:Ap3b1 APN 13 94545353 critical splice donor site probably null
IGL02119:Ap3b1 APN 13 94598911 missense probably benign 0.01
IGL02247:Ap3b1 APN 13 94531303 critical splice donor site probably null
IGL02303:Ap3b1 APN 13 94664827 missense unknown
IGL02493:Ap3b1 APN 13 94540528 missense probably damaging 0.98
IGL02551:Ap3b1 APN 13 94554599 missense probably damaging 0.99
IGL02651:Ap3b1 APN 13 94613529 missense probably damaging 1.00
IGL02832:Ap3b1 APN 13 94664835 missense unknown
IGL03033:Ap3b1 APN 13 94585003 missense probably benign 0.15
IGL03101:Ap3b1 APN 13 94591906 missense probably benign 0.00
bella UTSW 13 94664765 missense unknown
cuttlefish UTSW 13 94584959 critical splice acceptor site probably null
Gastropod UTSW 13 94679348 missense unknown
razor UTSW 13 94630239 missense unknown
Slime UTSW 13 94540586 missense possibly damaging 0.51
slug UTSW 13 94545353 critical splice donor site probably null
snail UTSW 13 94616393 splice site probably benign
stalk UTSW 13 94609439 critical splice donor site probably null
R0034:Ap3b1 UTSW 13 94616393 splice site probably benign
R0265:Ap3b1 UTSW 13 94630189 missense unknown
R0270:Ap3b1 UTSW 13 94540626 splice site probably benign
R0346:Ap3b1 UTSW 13 94582479 nonsense probably null
R0422:Ap3b1 UTSW 13 94598968 missense probably damaging 0.99
R0496:Ap3b1 UTSW 13 94609446 splice site probably benign
R0508:Ap3b1 UTSW 13 94702222 missense unknown
R0764:Ap3b1 UTSW 13 94616387 splice site probably benign
R1506:Ap3b1 UTSW 13 94582651 splice site probably benign
R1593:Ap3b1 UTSW 13 94638435 missense unknown
R1660:Ap3b1 UTSW 13 94545320 missense probably damaging 0.98
R1735:Ap3b1 UTSW 13 94630225 missense unknown
R1791:Ap3b1 UTSW 13 94545305 missense possibly damaging 0.63
R1818:Ap3b1 UTSW 13 94608212 missense possibly damaging 0.48
R2280:Ap3b1 UTSW 13 94664724 missense unknown
R3031:Ap3b1 UTSW 13 94702151 missense unknown
R3037:Ap3b1 UTSW 13 94582486 critical splice donor site probably null
R4401:Ap3b1 UTSW 13 94554607 missense probably damaging 1.00
R4402:Ap3b1 UTSW 13 94554607 missense probably damaging 1.00
R4403:Ap3b1 UTSW 13 94554607 missense probably damaging 1.00
R4532:Ap3b1 UTSW 13 94702243 missense unknown
R4624:Ap3b1 UTSW 13 94619734 missense unknown
R4626:Ap3b1 UTSW 13 94540586 missense possibly damaging 0.51
R4754:Ap3b1 UTSW 13 94540468 missense probably damaging 1.00
R4788:Ap3b1 UTSW 13 94702149 missense unknown
R4847:Ap3b1 UTSW 13 94608287 missense probably benign 0.15
R4886:Ap3b1 UTSW 13 94609313 missense possibly damaging 0.50
R5096:Ap3b1 UTSW 13 94616357 missense unknown
R5628:Ap3b1 UTSW 13 94613556 missense unknown
R5671:Ap3b1 UTSW 13 94664765 missense unknown
R5677:Ap3b1 UTSW 13 94664704 missense unknown
R5862:Ap3b1 UTSW 13 94684278 missense unknown
R5941:Ap3b1 UTSW 13 94619773 missense probably damaging 0.96
R5941:Ap3b1 UTSW 13 94576781 missense probably benign 0.02
R6043:Ap3b1 UTSW 13 94613501 missense probably benign 0.09
R6212:Ap3b1 UTSW 13 94630207 missense unknown
R6212:Ap3b1 UTSW 13 94587581 missense probably damaging 1.00
R6301:Ap3b1 UTSW 13 94664803 missense unknown
R6765:Ap3b1 UTSW 13 94599017 missense probably benign 0.02
R6812:Ap3b1 UTSW 13 94616369 missense unknown
R6888:Ap3b1 UTSW 13 94545299 missense probably benign 0.42
R6901:Ap3b1 UTSW 13 94554650 missense probably benign 0.00
R7157:Ap3b1 UTSW 13 94668542 nonsense probably null
R7422:Ap3b1 UTSW 13 94664673 missense unknown
R7642:Ap3b1 UTSW 13 94613540 missense probably benign 0.19
R7710:Ap3b1 UTSW 13 94587581 missense probably damaging 1.00
R7757:Ap3b1 UTSW 13 94664666 splice site probably null
R7867:Ap3b1 UTSW 13 94619771 missense unknown
R8492:Ap3b1 UTSW 13 94531294 missense possibly damaging 0.60
R8706:Ap3b1 UTSW 13 94545353 critical splice donor site probably null
R8749:Ap3b1 UTSW 13 94664725 missense unknown
R8876:Ap3b1 UTSW 13 94540586 missense possibly damaging 0.51
R8889:Ap3b1 UTSW 13 94679348 missense unknown
R8892:Ap3b1 UTSW 13 94679348 missense unknown
R9065:Ap3b1 UTSW 13 94608223 missense probably damaging 1.00
R9152:Ap3b1 UTSW 13 94630239 missense unknown
R9152:Ap3b1 UTSW 13 94609439 critical splice donor site probably null
R9166:Ap3b1 UTSW 13 94608236 missense probably damaging 1.00
R9218:Ap3b1 UTSW 13 94584959 critical splice acceptor site probably null
R9269:Ap3b1 UTSW 13 94540570 missense probably damaging 1.00
Mode of Inheritance Autosomal Recessive
Local Stock Embryos, Sperm, gDNA
MMRRC Submission 030291-UCD
Last Updated 2021-11-22 7:46 AM by Diantha La Vine
Record Created unknown
Record Posted 2007-09-28
Phenotypic Description

The bullet gray phenotype was detected among ENU-induced homozygous mutant G3 mice. Bullet gray mice display light-colored fur, with a mixture of white and gray-brown hairs. The ears, feet and tail have a light pink color, while the eyes are black (Figure 1). As with the souris, sooty, salt and pepper and toffee phenotypes, bullet gray confers enhanced susceptibility to mouse cytomegalovirus (MCMV) infection (MCMV Susceptibility and Resistance Screen). Bullet gray is allelic to pearl (1;2). Bullet gray and pearl mice also display reduced type I interferon (IFN) responses to CpG DNA challenge in vivo (Figure 2A) (3). This screen is designed to identify mutations that specifically affect plasmacytoid dendritic cell (pDC) development and function as pDCs are the primary type I IFN producing cell type in response to Toll-like receptor 9 (TLR9), which senses CpG DNA.  Further analysis of Ap3b1pearl/pearl mice revealed that although splenic pDCs are present (Figure 2B) and can be generated in vitro from bone marrow using FLT3 ligand (see the record for warmflash), the cells cannot produce type I IFN and the proinflammatory cytokine tumor necrosis factor (TNF)-α  in response to TLR9 stimulation (Figure 2C). Conventional DCs generated in vitro from GM-CSF treated Ap3b1pearl/pearl bone marrow are functionally normal (Figure 2D). Treatment of pDCs at the time of CpG stimulation with an inhibitor of the AP-3 activating GTP binding protein ARF1 also results in inhibition of type I IFN gene induction by pDCs (Figure 2E).   

Nature of Mutation
The bullet gray mutation is a G to T transversion in the donor splice site of intron 13 (GTGAGT -> TTGAGT) in the Ap3b1 gene on chromosome 13 (position 92056 in Genbank genomic region NC_000079 for linear genomic DNA sequence of Ap3b1). The mutation is predicted to result in skipping of the 133-nucleotide exon 13 (out of 27 total exons), destroying the reading frame in the middle of the encoded β3A polypeptide chain (aberrant amino acids after position 411), and creating a premature stop codon that would truncate the protein after amino acid 412.  The effect of the mutation at the cDNA and protein level has not been tested.
      <--exon 12  <--exon 13 intron 13-->  exon 14-->
89477  GAATTTCAG……AACAGGGATG GTGAGTTCA……………AAATAGTTGTTG 96377
405    -E--F--Q-……-N--R--D--               -Q--*        412
         correct    deleted                aberrant
The donor splice site of intron 13, which is destroyed by the bullet gray mutation, is indicated in blue lettering; the mutated nucleotide is indicated in red lettering.
Illustration of Mutations in
Gene & Protein
Protein Prediction

Figure 3. The AP-3 molecule consists of β3A-, δ-, μ3-, and σ3- subunits. The β3A and δ-subunits have three domains: the trunk (alternatively, head or core) region, which mediates protein-protein interactions with the other subunits, the hydrophilic hinge region and the ear or appendage region. The protein truncation caused by the bullet gray mutation is indicated by the red, wavy line and removes a portion of the trunk, the hinge and the ear.

AP-3 is one of four different heterotetrameric adaptor protein complexes (AP-1 to AP-4) in mammalian cells that decorate the cytoplasmic surface of membrane-bound vesicles at all levels from the trans-Golgi complex to the plasma membrane and direct subcelluar trafficking of membrane cargo proteins (4).  The subunits of AP complexes are called “adaptins” or “adaptin binding proteins,” and two large, one medium, and one small adaptin subunit are present in each AP complex.  The AP-3 complex is composed of β3, δ, μ3 and σ3 subunits, with each subunit existing in A (ubiquitous) and B (neuronal) isoforms encoded by distinct genes.  The 1105 amino acid β3A protein is one of the large subunits of the AP-3 complex and shares homology with the β1 and β2 subunits of the AP-1 and AP-2 complexes, respectively (5), and β-nonclathrin-associated phosphoprotein (NAP). For more information on the AP-3 complex, please see the record for christian.
 
The AP-1 and AP-2 complexes have an overall shape reminiscent of a “head” with two protruding “ears” separated by a hinge region, and it is believed that AP-3 has the same general shape (Figure 3) (6-8).  The A (“amino terminal” or "head") region (alternatively, the trunk domain) contains 12-13 Armadillo repeats, known to function in other settings as protein-protein interaction domains (9).  The H (“hinge”) region is strongly hydrophilic and rich in serine and acidic residues, and the C (“carboxy terminal”) region corresponds to an “ear” of the holoprotein complex.  The native human ortholog (obtained from M1 cells) has been detected in a phosphorylated state, likely reflecting phosphorylation of serine residues found in the H region (5).
Expression/Localization
Ap3b1 transcript was detected by Northern blot analysis in all human tissues examined, including heart, brain, placenta, lung, liver, skeletal muscle, kidney, and pancreas (5), and is also ubiquitously expressed in the mouse. The distribution of AP-3 complex was examined in NRK and MDBK cells (rat and bovine kidney cell lines, respectively), and found to co-localize with the trans-Golgi network (TGN) (10). AP-3 also decorates budding profiles on tubular endosomal compartments, likely on the way to lysosomes (11). The association of AP-3 with membranes is reportedly promoted by the small GTP-binding protein ARF-1 (ADP ribosylation factor-1) (12), although there has been no genetic confirmation of this interaction.
 
AP-1 and AP-2 bind clathrin directly, linking clathrin lattices to membranes within cells (4).  The human AP-3 complex has been reported to associate with clathrin in vitro and in HeLa cells (11;13;14).  However, another report indicated that it was not associated with clathrin, and controversy remains as to whether AP-3 function is clathrin-dependent (10;15).  Studies in yeast support a clathrin-independent function for AP-3 [reviewed in (16)].
Background
Hermansky-Pudlak syndromes (HPS; OMIM #203300) are a group of heterogeneous, autosomal recessive disorders caused by alterations at numerous independent loci (17).  Oculocutaneous albinism (OCA) and prolonged bleeding due to impaired platelet aggregation are common to all forms of HPS, but additional manifestations characterize specific types of HPS, such as pulmonary fibrosis (HPS-1 and HPS-4), and neutropenia and mild immunodeficiency (HPS-2). At the cellular level, HPS is caused by defects in the biogenesis of lysosome-related organelles, such as melanosomes, platelet dense granules, lamellar bodies of type II alveolar epithelial cells, and lytic granules of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. In particular, the pigmentation and bleeding problems associated with all forms of HPS arise from defects in melanosomes and platelet dense granules.
 

Figure 5. The HPS proteins form several protein complexes (AP-3, BLOC-1, BLOC-2, and BLOC-3) that are involved in trafficking of proteins to lysosomal-related organelles (LROs) from the TGN and affect the synthesis of these organelles.  Particular HPS complexes may affect only a subset of LROs (see text).  It is thought that BLOC-1 and AP-3 mediate early steps of vesicle trafficking from the early endosome, while BLOC-2 and BLOC-3 are likely involved at later stages.  Studies have shown physical interactions between BLOC-1 and AP-3, and BLOC-1 and BLOC-2. For simplicity, only the major cargo proteins affected by each HPS complex are shown (ATP7A, tyrosinase, Tyrp1, LAMP1).  The presence of ATP7A in maturing melanosomes allows the influx of copper and activates tyrosinase.  BLOC-1 is known to bind to the vesicle fusion protein syntaxin 13, which is localized to the stage I melanosome/coated endosome.  BLOC-2 and AP-3 may interact with clathrin.  Melanosomal maturation is shown separately, along with the stages affected by mutations in each HPS complex.  Mutations in the d subunit of the AP-3 complex affect melanosomal maturation between stages III and IV, but, as mentioned above, the AP-3 complex likely mediates early vesicle trafficking.

Each type of HPS is defined by the identity of the causative mutated gene. Eight types of human HPS have been described, and mutations affecting at least 15 loci in mice create HPS-like disease. The human HPS loci and their mouse equivalents are as follows: HPS1/pale ear (18); HPS2/pearl (19); HPS3/cocoa (mutated in pam gray) (20); HPS4/light ear (21); HPS5/ruby-eye 2 (mutated in toffee and dorian gray) (22); HPS6/ruby-eye (mutated in stamper-coat) (21); HPS7/sandy (mutated in salt and pepper) (23); and HPS8/putatively reduced pigmentation (24).  Most HPS genes encode subunits of protein complexes involved in intracellular trafficking (25). Based on biochemical studies, it has been proposed that the HPS proteins assemble into four stable complexes (Figure 3): biogenesis of lysosome-related organelle complex (BLOC)-1, BLOC-2, BLOC-3, and the adaptor protein-3 (AP-3) complex.  The 200-230 kD BLOC-1 complex consists of pallidin, dysbindin, BLOC subunit 1 (BLOS1), BLOS2, BLOS3, cappuccino, muted (mutated in minnie), and snapin.  BLOC-2 (350 kD) is composed of HPS3, HPS5, and HPS6.  The proteins HPS1 and HPS4 comprise BLOC-3 (175 kD).  BLOC-1 has been shown to interact with both BLOC-2 and AP-3 (26). Thus far, no interaction partner for BLOC-3 has been described (27).
 
Mutations in the β3A subunit of the AP-3 complex cause HPS-2 (OMIM #608233) (18;27-30). The AP complexes transport cargo proteins between components of the endocytic pathway, and AP-3 specifically shuttles proteins from the TGN to lysosomes and lysosome-related organelles (16;32).  Mutations of β3A are sufficient to dissociate the AP-3 complex and induce degradation of the other subunits (19;31).  Cargo recognition by AP-3 occurs through both tyrosine-based and dileucine-based lysosomal targeting motifs.  Thus, lysosome-associated membrane protein-1 (LAMP-1), LAMP-2, and CD63, cargo proteins for AP-3 which are sorted via tyrosine-based signals, fail to be recruited to lysosomes and accumulate at the plasma membrane in human fibroblasts with greatly reduced levels of AP-3 due to a mutation in β3A (11;19;20;33). Biochemical experiments demonstrate that AP-3 associates with dileucine-based signals of tyrosinase and lysosomal integral membrane protein-II (LIMP-II), but not other proteins containing dileucine motifs (33;34).  Tyrosinase and LIMP-II also accumulate at the cell membrane in AP-3 deficient cells (33).  
 
In addition to albinism and platelet aggregation deficiency, humans with HPS-2 exhibit neutropenia and immunodeficiency due to defects in NK cells and CTLs (28-30;35). In mice, mutations in the β3A subunit result in the pearl phenotype, which is characterized by hypopigmentation, lysosomal secretion abnormalities, and platelet-dense granules containing reduced levels of adenine nucleotides and serotonin (1).  Mutations in the mouse δ subunit of the AP-3 complex cause the similar mocha phenotype, with coat and eye color dilution, lysosomal abnormalities, platelet defects, and neurological defects (balance problems, deafness) (36)
 
Interestingly, a particular mutation of AP3B1 in dogs, an insertion of an A residue within a tract of nine A residues in exon 20, results in canine cyclic neutropenia, also known as gray Collie syndrome because the dogs have a diluted coat color (37). The mutation leads to a frameshift and premature termination, and absent mRNA due to nonsense-mediated decay (38). Humans with cyclic neutropenia display three week oscillations in the circulating neutrophil count, with fluctuations between near zero and near normal levels (39). Monocytes also cycle in the opposite phase to neutrophils. In dogs, neutrophil counts cycle every two weeks, and all other blood cells cycle in opposite phase. No pigmentation defects are observed in humans with cyclic neutropenia. Mutations in ELA2, encoding neutrophil elastase (NE), cause all known cases of human cyclic neutropenia (40). The enzyme NE (also known as leukocyte elastase) is a serine protease of neutrophil and monocyte granules, and cleaves many substrates including extracellular matrix proteins, clotting factors, immunoglobulins, and bacterial components, promoting microbe and tissue destruction (41;42). A yeast two-hybrid assay for testing adaptor protein subunit and cargo protein interactions indicates that the μ3A subunit of AP-3 interacts with NE via a tyrosine-based recognition signal, suggesting that NE is an AP-3 cargo protein (37).  The mistrafficking of NE as a result of mutations in either NE (that prevent recognition of the tyrosine-based signal by AP-3) or AP-3 is thought to underlie cyclic neutropenia (43).
Putative Mechanism
The bullet gray mutation creates a premature stop codon early in the Ap3b1 sequence (amino acid 421 out of 1105), possibly resulting in degradation of the protein, and at minimum abrogating most protein function.  Thus, the integrity of the AP-3 complex would likely be compromised. In mammals, melanin pigments conferring skin, hair and eye color are tyrosine-derived polymers synthesized in the melanosomes of melanocytes (16).  Incorrect targeting of AP-3 protein cargo, such as the melanin-biosynthetic enzyme tyrosinase (mutated in ghost) to melanosomes, would account for the hypopigmentation of bullet gray animals.  However, the presence of a significant amount of lysosomal membrane proteins in lysosomes of AP-3-deficient cells suggests the existence of an AP-3-independent pathway (19).
 
The MCMV susceptibility and lack of response to CpG stimulation suggests that the AP-3 complex is necessary for certain aspects of the immune response likely by affecting the trafficking and biogenesis of lytic granules in NK and/or T cells and an undefined subcellular compartment in pDCs (44). DCs are immune cells, whose main function is to process antigen material and present it on the surface to other cells of the immune system, thus functioning as antigen-presenting cells (APCs).  They activate helper T cells, cytotoxic T cells, and B cells, by presenting them with antigens derived from the pathogen, along with non-antigen specific costimulatory signals.  pDCs are a rare subtype of circulating DCs found in the blood as well as in peripheral lymphoid organs.  They are distinguished from conventional DCs by being derived from lymphoid precursors rather than myeloid precursors, and by differences in cell-surface markers (45).  As components of the innate immune system, these cells express endosomally-localized TLR7 and TLR9, which enable the detection of internalized viral and bacterial nucleic acids, such as ssRNA (via TLR7) or CpG DNA (via TLR9).  TLR7 and 9 signaling occurs via the adaptor protein myeloid differentiation (MyD) 88 (see pococurante and lackadaisical) resulting in the activation of the NF-κB pathway and production of proinflammatory cytokines such as TNF-α (see panr1), as well as the production of large amounts of type I IFN.  Type I IFNs are pleiotropic anti-viral proteins mediating a wide range of effects. Both TNF-α and type I IFN production by pDCs depends on components of the MyD88 signaling pathway including interleukin receptor associated kinase (IRAK)-1 and IRAK-4 (see otiose), interferon response factor (IRF) 5, TNF receptor–associated factor 6 (TRAF6), inhibitor of kappa-B kinase-α (IKKα), osteopontin, and IRF7 (see the record for inept) [reviewed in (46,47)].  The multispanning ER membrane protein UNC93B (mutated in 3d), which is required for trafficking of TLRs 3, 7, and 9 to the endosomal compartment (48), is also necessary for pDCs to sense nucleic acids. pDCs from TLR9-deficient or TLR7-deficient mice (see records for CpG1 and rsq1) fail to produce type I IFN in response to various viral and bacterial pathogens [reviewed by (49)].  An acidic endosomal environment has been shown to be essential for appropriate TLR7 and TLR9 signaling (50-52).
 
LROs share various characteristics with lysosomes and endolysosomes, such as an acidic intralumenal pH (53), and it is possible that trafficking and biogenesis of the endosomal or similar compartment in pDCs is also dependent on HPS proteins including AP-3. Indeed, analysis of DC generated from pearl homozygous mice suggests that AP-3 is required for the type I IFN response by trafficking TLR9 to a specialized subcellular compartment  (44). Interestingly, the pDC-specific phenotypes identified in mice with mutations in Ap3b1 parallel those found in mice homozygous for a mutation in Slc15a4 (see the record for feeble), which encodes PHT1, a proton-dependent oligopeptide transporter (3). PHT1 contains a typical acidic di-leucine motif required for AP-3 transport. PHT1 may regulate endosomal TLR7 and TLR9 signaling either by transporting a critical component into or out of the endosome, or by maintaining the appropriate pH necessary for TLR activation. Thus, AP-3 may be required to transport multiple proteins required for TLR signaling to their appropriate subcellular location. Mice carrying the salt and pepper allele of Dtnbp1, which encodes dysbindin, and the toffee allele of Hps5 also failed to produce type I IFN after in vivo challenge with CpG DNA.
Primers Primers cannot be located by automatic search.
Genotyping
Bullet gray genotyping is performed by amplifying the region containing the mutation using PCR, followed by sequencing of the amplified region to detect the single nucleotide transversion.  This protocol has not been tested.
 
Primers
bullet gray(F): 5’- ACCCTGGCTTGAAAATGTCCCTTTG -3’
bullet gray(R): 5’- CGACTTCCACGCATGACTAGGAAAC -3’
 
PCR program
1) 95°C             2:00
2) 95°C             0:30
3) 56°C             0:30
4) 72°C             1:00
5) repeat steps (2-4) 29X
6) 72°C             7:00
7) 4°C              ∞
 
Primers for sequencing
bullet gray_seq(F): 5’- ACGTTAAGCAATCATTTGGGGC -3’
bullet gray_seq(R): 5’- TATGAAGCAGTGCTTAGTGAATG -3’
 
The following sequence of 621 nucleotides (from Genbank genomic region NC_000079 for linear genomic sequence of Ap3b1) is amplified:
 
91806      accct ggcttgaaaa tgtccctttg ccaaagggac attaagttat aagcgatgaa
91861 agacgttaag caatcatttg gggcccctgt taggcttaag agaattctaa attttttgtc
91921 ctgacaaagc tataaaaatg ggctttgatt cacttgataa cgccaatgtt gaaactaatc
91981 aaactgtttt tagacctacg tgagaagcca ggacaaacag tttgcagcag ccactattca
92041 gaccataggc agatgtgcaa ccagcattag cgaggtcacc gacacatgcc tcaacggcct
92101 ggtctgcctg ctgtccaaca gggatggtga gttcataggt tcactttatt tttatatggt
92161 tcataattgt atattctcag taagtcctat agctgtaatc tattatatta tcttttcggg
92221 tttttctata tatcagtatt ttctcagtaa gtagcagctt tattcttgat ttgcaggaaa
92281 atttatttca aaaaataaat gagataatta atagattttg ttttgctccc attaagacaa
92341 tttatcttac tcattcacta agcactgctt catacccttt ctgcaaaggt tctctgtgac
92401 tgtttcctag tcatgcgtgg aagtcg
 
Primer binding sites are underlined; sequencing primer binding sites are highlighted in gray; the mutated G is highlighted in red.
References
 16.  Odorizzi, G., Cowles, C. R., and Emr, S. D. (1998) The AP-3 complex: a coat of many colours, Trends Cell Biol. 8, 282-288.
 17.  Huizing, M., Boissy, R. E., and Gahl, W. A. (2002) Hermansky-Pudlak Syndrome: Vesicle Formation from Yeast to Man. Pigment Cell Res. 15, 405-419.
 18.  Oh, J., Bailin, T., Fukai, K., Feng, G. H., Ho, L., Mao, J. I., Frenk, E., Tamura, N., and Spritz, R. A. (1996) Positional cloning of a gene for Hermansky-Pudlak syndrome, a disorder of cytoplasmic organelles, Nat. Genet. 14, 300-306.
 19.  Dell'angelica, E. C., Shotelersuk, V., Aguilar, R. C., Gahl, W. A., and Bonifacino, J. S. (1999) Altered trafficking of lysosomal proteins in Hermansky-Pudlak syndrome due to mutations in the beta 3A subunit of the AP-3 adaptor, Mol. Cell 3, 11-21.
 20.  Anikster, Y., Huizing, M., White, J., Shevchenko, Y. O., Fitzpatrick, D. L., Touchman, J. W., Compton, J. G., Bale, S. J., Swank, R. T., Gahl, W. A., and Toro, J. R. (2001) Mutation of a new gene causes a unique form of Hermansky-Pudlak syndrome in a genetic isolate of central Puerto Rico, Nat. Genet. 28, 376-380.
 21.  Suzuki, T., Li, W., Zhang, Q., Karim, A., Novak, E. K., Sviderskaya, E. V., Hill, S. P., Bennett, D. C., Levin, A. V., Nieuwenhuis, H. K., Fong, C. T., Castellan, C., Miterski, B., Swank, R. T., and Spritz, R. A. (2002) Hermansky-Pudlak syndrome is caused by mutations in HPS4, the human homolog of the mouse light-ear gene, Nat. Genet. 30, 321-324.
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Science Writers Alyson Mack, Eva Marie Y. Moresco
Illustrators Diantha La Vine, Katherine Timer
AuthorsSophie Rutschmann, Amanda L. Blasius, Bruce Beutler
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