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Protein tyrosine phosphatase, receptor type, C
PDB rendering based on 1ygr.
Available structures: 1ygr, 1ygu
Symbol(s) PTPRC; LCA; B220; CD45; GP180; LY5; T200
External IDs OMIM: 151460 MGI: 97810 Homologene: 2126
RNA expression pattern

More reference expression data

Human Mouse
Entrez 5788 19264
Ensembl ENSG00000081237 ENSMUSG00000026395
Uniprot P08575 Q5XFY7
Refseq NM_002838 (mRNA)
NP_002829 (protein)
NM_011210 (mRNA)
NP_035340 (protein)
Location Chr 1: 196.87 - 196.99 Mb Chr 1: 139.88 - 139.99 Mb
Pubmed search [1] [2]

In immunology, the CD45 antigen (CD stands for cluster of differentiation) is a protein which was originally called leukocyte common antigen.

It is a type I transmembrane protein which is in various forms present on all differentiated hematopoietic cells except erythrocytes and plasma cells that assists in the activation of those cells (a form of co-stimulation).

It is expressed in lymphomas, B-cell chronic lymphocytic leukemia, hairy cell leukemia, and acute nonlymphocytic leukemia.

The CD45 family consists of multiple members that are all products of a single complex gene. This gene contains 34 exons and three exons of the primary transcripts are alternatively spliced to generate up to eight different mature mRNAs and after translation eight different protein products. This three exons generate the RA, RB and RC isoforms.

Various isoforms of CD45 exist: CD45RA, CD45RB, CD45RC, CD45RAB, CD45RAC, CD45RBC, CD45RO, CD45R (ABC). CD45 is also highly glycosylated. CD45R is the longest protein and migrates at 200 kDa when isolated from T cells. B cells also express CD45R with heavier glycosylation, bringing the molecular weight to 220 kDa, hence the name B220; B cell isoform of 220 kDa. B220 expression is not restricted to B cells and can also be expressed on activated T cells, on a subset of dendritic cells and other antigen presenting cells.

Naive T lymphocytes express large CD45 isoforms and are usually positive for CD45RA. Activated and memory T lymphocytes express the shortest CD45 isoform, CD45RO, which lacks RA, RB and RC exons. This shortest isoform facilitates T cell activation.

The cytoplasmic domain of CD45 is one of the largest known and it has an intrinsic phosphatase activity that removes an inhibitory phosphate group on a tyrosine kinase called Lck (in T cells) or Syk (in B cells) and activates it.


    Further reading

    • Tchilian EZ, Beverley PC (2002). "CD45 in memory and disease.". Arch. Immunol. Ther. Exp. (Warsz.) 50 (2): 85-93. PMID 12022705.
    • Ishikawa H, Tsuyama N, Abroun S, et al. (2004). "Interleukin-6, CD45 and the src-kinases in myeloma cell proliferation.". Leuk. Lymphoma 44 (9): 1477-81. PMID 14565647.
    • Stanton T, Boxall S, Bennett A, et al. (2004). "CD45 variant alleles: possibly increased frequency of a novel exon 4 CD45 polymorphism in HIV seropositive Ugandans.". Immunogenetics 56 (2): 107-10. doi:10.1007/s00251-004-0668-z. PMID 15057492.
    • Huntington ND, Tarlinton DM (2005). "CD45: direct and indirect government of immune regulation.". Immunol. Lett. 94 (3): 167-74. doi:10.1016/j.imlet.2004.05.011. PMID 15275963.

    This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "CD45". A list of authors is available in Wikipedia.
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