pp125FAK a structurally distinctive protein-tyrosine kinase associated with focal adhesions.

TLDR

The oncogenic Rous sarcoma virus protein pp60v‑src drives cell growth by its intrinsic tyrosine‑kinase activity, increasing phosphorylation of cellular substrates. We isolated pp125, a cytoplasmic protein‑tyrosine kinase that is highly phosphorylated in pp60v‑src‑transformed cells, localizes to focal adhesions, and represents a new kinase family.

Abstract

Expression of the Rous sarcoma virus-encoded oncoprotein, pp60v-src, subverts the normal regulation of cell growth, which results in oncogenic transformation. This process requires the intrinsic protein-tyrosine kinase activity of pp60v-src and is associated with an increase in tyrosine phosphorylation of a number of cellular proteins, candidate substrates for pp60v-src. We report here the isolation of a cDNA encoding a protein, pp125, that is a major phosphotyrosine-containing protein in untransformed chicken embryo cells and exhibits an increase in phosphotyrosine in pp60v-src-transformed chicken embryo cells. This cDNA encodes a cytoplasmic protein-tyrosine kinase which, based upon its predicted amino acid sequence and structure, is the prototype for an additional family of protein-tyrosine kinases. Immunofluorescence localization experiments show that pp125 is localized to focal adhesions; hence, we suggest the name focal adhesion kinase.