PTPRC is a transmembrane protein tyrosine phosphatase expressed on the surface of all nucleated hematopoietic cells, particularly lymphocytes.

It functions by dephosphorylating specific tyrosine residues on target proteins, thereby controlling various signaling processes essential for immune response and homeostasis.

PTPs are signaling molecules that regulate a variety of cellular processes including cell growth, differentiation, mitotic cycle, and oncogenic transformation.

[citation needed] Many alternatively spliced transcripts variants of this gene, which encode distinct isoforms, have been reported.

[11] CD45's large extracellular domain is highly glycosylated, and these eight isoforms allow wide variation in the structure of its side chains.

The isoforms affect the protein's N-terminal region, which extends linearly out from the cell and bears the O-linked glycan chains.

[citation needed] CD45 isoforms show cell-type and differentiation-stage specific expression, a pattern which is quite well conserved in mammals.

[20] CD45 is a pan-leukocyte protein with tyrosine phosphatase activity involved in the regulation of signal transduction in hematopoiesis.

This strain was designed for competitive bone marrow transplantation assays and demonstrated perfect equivalence, unlike the previous standard, the "SJL" mouse, more formally known as Pep Boy.