Phosphatase Subfamily PTPRC

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Phosphatase Classification: Fold CC1: Superfamily CC1: Family PTP: Subfamily PTPRC

PTPRC (CD45) is a vertebrate-specific receptor PTP involved in immune signaling.


PTPRC is found as a single-copy gene in all vertebrates, including the lamprey, but not in any invertebrate.


PTPRC has twin intracellular PTP phosphatase domains, and extracellular FN3 domains, plus a CD45-specific and a PTP-N-terminal domain found specifically in PTPRC, as annotated by InterPro. CD45 is extensively alternatively spliced.

Second phosphatase domain (D2) is inactive

The functional role of the D2 domain has not yet been defined although possible roles in regulating RPTP stability, specificity, and dimerization have been suggested [1].


CD45 modulates immune function [2]. It is selectively expressed on lymphocytes and dephosphorylates and activates the src family tyrosine kinases lck, fyn and lyn in B and T cells.


PTPRC (CD45) is used in CellSearch system to detect circulating tumor cell.


  1. Barr AJ, Ugochukwu E, Lee WH, King ON, Filippakopoulos P, Alfano I, Savitsky P, Burgess-Brown NA, Müller S, and Knapp S. Large-scale structural analysis of the classical human protein tyrosine phosphatome. Cell. 2009 Jan 23;136(2):352-63. DOI:10.1016/j.cell.2008.11.038 | PubMed ID:19167335 | HubMed [Barr09]
  2. Furlan G, Minowa T, Hanagata N, Kataoka-Hamai C, and Kaizuka Y. Phosphatase CD45 both positively and negatively regulates T cell receptor phosphorylation in reconstituted membrane protein clusters. J Biol Chem. 2014 Oct 10;289(41):28514-25. DOI:10.1074/jbc.M114.574319 | PubMed ID:25128530 | HubMed [furlan14]
All Medline abstracts: PubMed | HubMed