|Coordinate||138,071,249 bp (GRCm38)|
|Base Change||A ⇒ T (forward strand)|
|Gene Name||protein tyrosine phosphatase, receptor type, C|
|Synonym(s)||B220, Ly-5, Lyt-4, CD45, T200|
|Chromosomal Location||138,062,861-138,175,708 bp (-)|
FUNCTION: [Summary is not available for the mouse gene. This summary is for the human ortholog.] The protein encoded by this gene is a member of the protein tyrosine phosphatase (PTP) family. PTPs are known to be signaling molecules that regulate a variety of cellular processes including cell growth, differentiation, mitosis, and oncogenic transformation. This PTP contains an extracellular domain, a single transmembrane segment and two tandem intracytoplasmic catalytic domains, and thus is classified as a receptor type PTP. This PTP has been shown to be an essential regulator of T- and B-cell antigen receptor signaling. It functions through either direct interaction with components of the antigen receptor complexes, or by activating various Src family kinases required for the antigen receptor signaling. This PTP also suppresses JAK kinases, and thus functions as a regulator of cytokine receptor signaling. Alternatively spliced transcripts variants of this gene, which encode distinct isoforms, have been reported. [provided by RefSeq, Jun 2012]
PHENOTYPE: Homozygous null mutants have defective T cell, B cell, and NK cell morphology and physiology. Mice carrying an engineered point mutation exhibit lymphoproliferation and autoimmunity that leads to premature death. [provided by MGI curators]
|Amino Acid Change||Methionine changed to Lysine|
|Institutional Source||Beutler Lab|
|Gene Model||predicted gene model for protein(s): [ENSMUSP00000138800] [ENSMUSP00000138275] [ENSMUSP00000138350]|
|Predicted Effect||noncoding transcript|
AA Change: M882K
|Predicted Effect||probably damaging
PolyPhen 2 Score 0.980 (Sensitivity: 0.75; Specificity: 0.96)
AA Change: M858K
|Predicted Effect||probably damaging
PolyPhen 2 Score 0.984 (Sensitivity: 0.74; Specificity: 0.96)
AA Change: M1021K
|Predicted Effect||possibly damaging
PolyPhen 2 Score 0.722 (Sensitivity: 0.86; Specificity: 0.92)
|Meta Mutation Damage Score||0.6970|
|Is this an essential gene?||Possibly nonessential (E-score: 0.268)|
|Candidate Explorer Status||CE: excellent candidate; human score: 0; ML prob: 0.574|
Linkage Analysis Data
|Alleles Listed at MGI|
|Mode of Inheritance||Unknown|
|Last Updated||2019-09-04 9:35 PM by Diantha La Vine|
|Record Created||2018-05-27 1:32 PM by Bruce Beutler|
The Half_measure phenotype was identified among G3 mice of the pedigree R6026, some of which showed increased frequencies of CD44+ T cells (Figure 1). Some mice also showed increased CD44 expression on CD44 T cells (Figure 2) and CD44+ CD4 T cells (Figure 3).
|Nature of Mutation|
Whole exome HiSeq sequencing of the G1 grandsire identified 75 mutations. All of the above anomalies were linked by continuous variable mapping to a mutation in Ptprc: a T to A transversion at base pair 138,071,249 (v38) on chromosome 1, or base pair 104,508 in the GenBank genomic region NC_000067 encoding Ptprc. The strongest association was found with an additive model of inheritance to the CD44 expression on CD4 T cells, wherein six variant homozygotes and 10 heterozygous mice departed phenotypically from six homozygous reference mice with a P value of 4.57 x 10-5 (Figure 4).
The mutation corresponds to residue 3,101 in the mRNA sequence NM_001111316 within exon 29 of 33 total exons, residue 2,782 in the mRNA sequence NM_011210 within exon 26 of 30 total exons, and residue 2,710 in the mRNA sequence NM_001268286 within exon 25 of 29 total exons.
Genomic numbering corresponds to NC_000067. The mutated nucleotide is indicated in red. The mutation results in a methionine to lysine substitution at position 1,021 (M1021K) in variant 1 of the PTPRC protein (PolyPhen score = 0.918), a M882K substitution in variant 2 (PolyPhen score = 0.984), and a M858K substitution in variant 3 (PolyPhen score = 0.984).
Ptprc encodes CD45, a receptor-like protein tyrosine phosphatase (PTP) expressed by cells of the immune system. It is known by several names, including T200 (1), B220 for the B cell form (2), the mouse allotypic marker Ly-5 (3), and CD45. CD45 is a type I transmembrane glycoprotein containing a large N-terminal extracellular domain of ~400-500 residues (depending on the expression of several alternative exons, see below), a single transmembrane domain (22 amino acids), and a C-terminal cytoplasmic domain of 707 residues containing tandem PTP domains only one of which is enzymatically active. Following the PTP domains is a 79 residue C-terminal tail.
Exons 4, 5, and 6 of Ptprc are alternatively spliced to generate three protein isoforms with variations in the most N-terminal domain, furtherst from the cell membrane. The three peptides are designated as A, B, and C, respectively. The protein isoforms are commonly named based on the exons included, with the largest isoform (RABC) including all three exons, RAB including exons 4 and 5, etc., and the smallest isoform lacking all three exons designated RO. The D2 domain is a protein tyrosine phosphatase (PTP) domain that is enzymatically inactive, but optimal phosphatase activity in cells requires both the D1 and the D2 domains (4). Within the D2 domain is a unique acidic region of 19 residues that contains multiple sites for serine phosphorylation by casein kinase II (5;6). This modification is important for optimal CD45 phosphatase activity toward a model substrate in vitro and for cellular signaling leading to Ca2+ flux in Jurkat T cells, although the mechanistic basis for these effects is unknown. The D2 domain may also modulate substrate access and localization, as suggested by the interaction of D2 with the CD45 substrate Lck (7).
The Half_measure mutation results in a methionine to lysine substitution at position 1,021 (M1021K) in variant 1 of the PTPRC protein; amino acid 1,021 is within the second PTP domain.
Please see the record for belittle for information about CD45.
The physiological function of CD45 has been examined most extensively in T cells. Studies with CD45-deficient cell lines identified CD45 as an obligate positive regulator of antigen receptor signaling, since T cells lacking CD45 failed to proliferate or produce cytokines in response to TCR stimulation (8;9). CD45 can regulate both the activating and inhibitory tyrosines of Src family kinases.
Ptprc-/- mice have profound defects in thymic development due to dysfunctional signaling through the preTCR and TCR, leading to a block in thymocyte development at β selection and at the DP stage (10-12). As a result, the absolute number of DP thymocytes is reduced twofold, and the number of single positive (SP) thymocytes is reduced five-fold. Peripheral B cell numbers are actually increased in CD45-deficient mice. CD45 deficiency has less severe consequences for B cells than for T cells. Peripheral B cell numbers are actually increased in CD45-deficient mice (10-12). Marginal zone B cells are increased, while B1 cell production is decreased, and B cell development is blocked at the transitional 2 (T2) to mature follicular B cell transition (13). Humans deficient in CD45 develop severe combined immunodeficiency (SCID) with defects in T and B cell development and function (OMIM #608971) (14;15).
The immune cell phenotype of the Half_measure mice is similar to that of the Ptprc-/- mice suggesting that the Half_measure mutation abrogates CD45 expression. The expression and localization of CD45Half_meaure have not been examined; however, the phenotype of the Half_measure mice indicates that the mice do not express functional CD45.
1) 94°C 2:00
The following sequence of 422 nucleotides is amplified (chromosome 1, - strand):
1 gacactgaac ttttcttggt cttcagaatc ttaactttgt ctattaatgg caatgatacc
Primer binding sites are underlined and the sequencing primers are highlighted; the mutated nucleotide is shown in red.
1. Trowbridge, I. S., and Mazauskas, C. (1976) Immunological Properties of Murine Thymus-Dependent Lymphocyte Surface Glycoproteins. Eur J Immunol. 6, 557-562.
2. Coffman, R. L., and Weissman, I. L. (1981) B220: A B Cell-Specific Member of Th T200 Glycoprotein Family. Nature. 289, 681-683.
3. Komuro, K., Itakura, K., Boyse, E. A., and John, M. (1974) Ly-5: A New T-Lymphocyte Antigen System. Immunogenetics. 1, 452-456.
4. Desai, D. M., Sap, J., Silvennoinen, O., Schlessinger, J., and Weiss, A. (1994) The Catalytic Activity of the CD45 Membrane-Proximal Phosphatase Domain is Required for TCR Signaling and Regulation. EMBO J. 13, 4002-4010.
5. Wang, Y., Guo, W., Liang, L., and Esselman, W. J. (1999) Phosphorylation of CD45 by Casein Kinase 2. Modulation of Activity and Mutational Analysis. J Biol Chem. 274, 7454-7461.
6. Greer, S. F., Wang, Y., Raman, C., and Justement, L. B. (2001) CD45 Function is Regulated by an Acidic 19-Amino Acid Insert in Domain II that Serves as a Binding and Phosphoacceptor Site for Casein Kinase 2. J Immunol. 166, 7208-7218.
7. Wang, Y., and Johnson, P. (2005) Expression of CD45 Lacking the Catalytic Protein Tyrosine Phosphatase Domain Modulates Lck Phosphorylation and T Cell Activation. J Biol Chem. 280, 14318-14324.
8. Pingel, J. T., and Thomas, M. L. (1989) Evidence that the Leukocyte-Common Antigen is Required for Antigen-Induced T Lymphocyte Proliferation. Cell. 58, 1055-1065.
9. Weaver, C. T., Pingel, J. T., Nelson, J. O., and Thomas, M. L. (1991) CD8+ T-Cell Clones Deficient in the Expression of the CD45 Protein Tyrosine Phosphatase have Impaired Responses to T-Cell Receptor Stimuli. Mol Cell Biol. 11, 4415-4422.
10. Mee, P. J., Turner, M., Basson, M. A., Costello, P. S., Zamoyska, R., and Tybulewicz, V. L. (1999) Greatly Reduced Efficiency of both Positive and Negative Selection of Thymocytes in CD45 Tyrosine Phosphatase-Deficient Mice. Eur J Immunol. 29, 2923-2933.
11. Byth, K. F., Conroy, L. A., Howlett, S., Smith, A. J., May, J., Alexander, D. R., and Holmes, N. (1996) CD45-Null Transgenic Mice Reveal a Positive Regulatory Role for CD45 in Early Thymocyte Development, in the Selection of CD4+CD8+ Thymocytes, and B Cell Maturation. J Exp Med. 183, 1707-1718.
12. Kishihara, K., Penninger, J., Wallace, V. A., Kundig, T. M., Kawai, K., Wakeham, A., Timms, E., Pfeffer, K., Ohashi, P. S., and Thomas, M. L. (1993) Normal B Lymphocyte Development but Impaired T Cell Maturation in CD45-exon6 Protein Tyrosine Phosphatase-Deficient Mice. Cell. 74, 143-156.
13. Hermiston, M. L., Tan, A. L., Gupta, V. A., Majeti, R., and Weiss, A. (2005) The Juxtamembrane Wedge Negatively Regulates CD45 Function in B Cells. Immunity. 23, 635-647.
14. Kung, C., Pingel, J. T., Heikinheimo, M., Klemola, T., Varkila, K., Yoo, L. I., Vuopala, K., Poyhonen, M., Uhari, M., Rogers, M., Speck, S. H., Chatila, T., and Thomas, M. L. (2000) Mutations in the Tyrosine Phosphatase CD45 Gene in a Child with Severe Combined Immunodeficiency Disease. Nat Med. 6, 343-345.
|Science Writers||Anne Murray|
|Illustrators||Diantha La Vine|
|Authors||Xue Zhong, Jin Huk Choi, and Bruce Beutler|