ACTIVATION OF HUMAN PP60(C-SRC)

pp60c-(src) and the structurally related members of the Src family are non-receptor tyrosine kinases that reside within the cell associated with cell membranes and appear to transduce signals from transmembrane receptors to the cell interior. Many intracellular pathways can be st imulated upon Src activation, and a Variety of cellular consequences c an result, including morphological changes and cell proliferation. pp6 0(c-src) activity is normally suppressed by phosphorylation on its car boxyterminal tail by an enzyme known as CSK. Various cellular stimuli or mutations within pp60(c-src) can activate its endogenous kinase act ivity. In this paper, we review aspects of pp60(c-src) activation and regulation and discuss results obtained in our laboratory in two exper imental systems: (i) in melanoma cell lines and primary pigmented norm al human melanocytes and (ii) using activated mutant forms of purified human pp60(c-src) protein.