Molecular cloning and chromosomal localization of a human gene homologous to the murine R-PTP-kappa, a receptor-type protein tyrosine phosphatase

Abstract

Tyrosine phosphorylation of proteins plays an important role in cellular signaling and many cellular activities. The levels of cellular phosphorylation are reversibly controlled by protein tyrosine kinases and protein tyrosine phosphatases. The murine R-PTP-kappa, a receptor-type protein tyrosine phosphatase, has recently been cloned (Jiang et al. (1993) Mol. Cell. Biol. 13, 2942-2951). In order to identify the protein tyrosine phosphatases critical to the cellular signal transduction in human keratinocytes, a polymerase chain reaction (PCR)-based strategy was employed, and we have cloned a human homologue of the murine R-PTP-kappa Here, we report the isolation of a complementary DNA encoding a human R-PTP-kappa. Of the several overlapping cDNA clones, one clone, which we originally termed p55-7, was found to encode a transmembrane protein of 1440 amino acids and was highly conserved with murine R-PTP-kappa with 98% identity at the amino-acid levels. The human R-PTP-kappa gene was localized to chromosome 6 by southern hybridization of DNA from a rodent/human somatic cell mapping panel. Northern blot analysis of RNA from several human tissues revealed, like the murine R-PTP-kappa, the presence of a major mRNA of approx. 7.0 kb and a minor mRNA of approx. 5.3 kb. In contrast to the expression of murine R-PTP-kappa