Journal article

MECHANISM OF C-SRC ACTIVATION IN HUMAN MELANOCYTES - ELEVATED LEVEL OF PROTEIN-TYROSINE-PHOSPHATASE ACTIVITY DIRECTED AGAINST THE CARBOXY-TERMINAL REGULATORY TYROSINE

TJ OCONNOR, JD BJORGE, HC CHENG, JH WANG, DJ FUJITA

CELL GROWTH & DIFFERENTIATION | AMER ASSOC CANCER RESEARCH | Published : 1995

Abstract

Normal human melanocytes, and some human melanoma cell lines, contain c-SRC which is constitutively activated by hypophosphorylation of tyrosine 530. We investigated the possibility that the activation of c-SRC in melanocytes might be attributable to elevated levels of tyrosine 530-directed protein tyrosine phosphatase activity in these cells. We found three times more of this phosphatase activity in cell extracts from melanocytes compared to fibroblasts. The majority of the tyrosine 530-dephosphorylating activity was present in the particulate fraction of cell homogenates, where c-SRC is also located. Treatment of melanocytes with the protein tyrosine phosphatase inhibitor, sodium orthovana..

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