Protein tyrosine phosphatase, receptor type, C (PTPRC)

Protein tyrosine phosphatase, receptor type, C (PTPRC), commonly known as CD45 or leukocyte common antigen, is a type I transmembrane receptor-type protein tyrosine phosphatase expressed on all nucleated hematopoietic cells, excluding erythrocytes and plasma cells[1][2][3]. CD45 is essential for regulating activation, differentiation, and survival of T and B lymphocytes and other immune cells. It functions by dephosphorylating critical tyrosine residues on signaling molecules—particularly members of the Src family kinases and other components of antigen receptor signaling complexes—thus controlling immune response, cell cycle, proliferation, and homeostasis. Dysregulation, aberrant expression, or mutation of PTPRC can result in immunodeficiencies, e.g., severe combined immunodeficiency, autoimmunity, leukemia, lymphoma, and other hematological disorders[1][2][3][7][9]. CD45 is a key marker for identifying leukocytes in clinical and research diagnostics and is a focus of interest for immune-targeted therapies, though currently direct pharmacological targeting in the clinic is not established.

Other names

CD45Leukocyte common antigen (LCA)T200GP180PTPRC

Dephosphorylation of tyrosine residues on signaling proteins (e.g., SFKs, LYN, FYN), regulation of antigen receptor signaling in lymphocytes, negative regulation of JAK-STAT pathway, modulation of cytokine production[1][2][3].