cDNA cloning of a novel protein tyrosine phosphatase with homology to cytoskeletal protein 4.1 and its expression in T-lineage cells.

Reversible tyrosine phosphorylation plays important regulatory roles in various cellular events including the differentiation and function of lymphocytes. Here we report the cDNA cloning of a non-receptor type protein tyrosine phosphatase, PTP36, which is expressed in murine thymus. PTP36 was a new member of a tyrosine phosphatase subfamily defined by MEG-01 and PTPH1, which had a C-terminal phosphatase domain as well as an N-terminal domain with homology to cytoskeletal-associated proteins like band 4.1, ezrin, and talin. In addition, we found a putative SH3-binding motif in PTP36 but not in MEG-01 or PTPH1. PTP36 was expressed in cells of both hematopoietic and non-hematopoietic origins. In thymocytes subpopulations, PTP36 was preferentially expressed in double positive stage cells. The change of PTP36 expression level along with T cell maturation suggests its involvement in the regulation of T cell development.