Protein tyrosine phosphatase receptor type C (PTPRC) is also known as CD45 antigen, which was originally called leukocyte common antigen (LCA). CD45 is an enzyme required for T-cell activation through the antigen receptor consisting of two intracellular phosphatase domains, a transmembrane domain and an extracellular domain. Upon T-cell activation, CD45 recruits and dephosphorylates SKAP1 via an interaction through the first PTPase domain, which is the only domain to possess intrinsic kinase activity. However, both domains are required for appropriate phosphatase and T-cell antigen receptor activity (PMID: 8076596).
What is the molecular weight of CD45?
The molecular weight of CD45 is a 180-240 kDa.
What are the isoforms of CD45?
Six different human isoforms of CD45 have been isolated, containing all three exons (ABC isoform), two of the three exons (AB and BC isoforms), only one exon (A isoform or B isoform), or no exons (O isoform). All of the isoforms have the same eight amino acids at their amino-terminus (PMID: 12412720).
What is the tissue specificity of CD45?
CD45 is a tyrosine phosphatase expressed on the plasma membrane of all hematopoietic cells, except erythrocytes and platelets (PMID: 7803253).
What are the post-translational modifications of CD45?
CD45 can be heavily N- and O-glycosylated (PMID: 1702721).
What is CD45’s involvement in disease?
Defects in CD45 are a cause of severe combined immunodeficiency autosomal recessive T-cell-negative/B-cell-positive/NK-cell-positive (T(-)B(+)NK(+) SCID); a severe form of SCID. It is classed by the impairment of both humoral and cell-mediated immunity, leukopenia, and the low or absent levels of antibodies (PMID: 10700239). Also, genetic variants of CD45 have a role in susceptibility to multiple sclerosis (PMID: 12864992).