Protein tyrosine phosphatase receptor type C (CD45RO) (CD45RO)

CD45RO is the shortest isoform of the Protein Tyrosine Phosphatase Receptor Type C (PTPRC), a transmembrane protein expressed on all nucleated hematopoietic cells. It is generated through alternative splicing of the PTPRC gene, specifically excluding exons 4, 5, and 6 (A, B, and C), resulting in a 180 kDa glycoprotein. CD45RO is a hallmark marker for memory and activated T cells, playing a vital role in modulating the sensitivity of T-cell and B-cell receptors to antigenic stimulation. By dephosphorylating the C-terminal inhibitory tyrosine of Src family kinases like Lck, it facilitates the initiation of downstream signaling cascades necessary for immune responses. In clinical practice, CD45RO expression is widely used as a prognostic biomarker in various malignancies, where high levels of CD45RO+ tumor-infiltrating lymphocytes often correlate with improved survival. Therapeutic targeting of CD45RO and other CD45 isoforms is being investigated for applications in hematopoietic stem cell transplantation, autoimmune disease management, and cancer immunotherapy.

Other names

PTPRCLeukocyte common antigenLCAT200GP180UCHL1 antigenCD45

CD45RO acts as a protein tyrosine phosphatase that dephosphorylates the inhibitory C-terminal tyrosine residue of Src family kinases, such as Lck and Fyn, which lowers the threshold for T-cell and B-cell receptor signaling and promotes lymphocyte activation. It also modulates cytokine receptor signaling by regulating JAK kinase phosphorylation.