PROLACTIN RECEPTOR IS ASSOCIATED WITH C-SRC KINASE IN RAT-LIVER

The mechanism of action of the pituitary hormone PRL was studied in hepatocytes of lactating rats. PRL receptor immune complexes obtained from liver lysates have an associated tyrosine kinase activity. The tyrosine kinase has been identified in isolated hepatocytes as pp60(c-src). Incubation of hepatocytes with PRL induces the association of PRL receptor with pp60(c-src) and the resultant stimulation of its tyrosine kinase activity. Furthermore, PRL stimulates the gene expression of c-fos, c-jun, and c-src. All of these findings support the idea that the pp60(c-src) tyrosine kinase participates in the early steps of the PRL intracellular signaling that promotes cell growth in liver cells.