Transformation-specific tyrosine phosphorylation of a novel cellular protein in chicken cells expressing oncogenic variants of the avian cellular src gene.

Reynolds AB, Roesel DJ, Kanner SB, Parsons JT
Mol Cell Biol. 1989 9 (2): 629-38

PMID: 2469003 · PMCID: PMC362640 · DOI:10.1128/mcb.9.2.629

We used myristylated and nonmyristylated c-src-based variants and phosphotyrosine-specific antibodies to reevaluate the role of tyrosine phosphorylation in cellular transformation by pp60src. Prior methods used to detect tyrosine-phosphorylated proteins failed to discriminate predicted differences in tyrosine phosphorylation which are clearly observed with phosphotyrosine-specific antibodies and Western blotting (immunoblotting). Here we report the observation of a 120,000-Mr protein whose phosphorylation on tyrosine correlates with the induction of morphological transformation. p120 was not observed in cells overexpressing the regulated, nononcogenic pp60c-src, whereas phosphorylation of p120 was greatly enhanced in cells expressing activated, oncogenic pp60527F. Furthermore, phosphorylation of p120 was not induced by expression of the activated but nonmyristylated src variant pp602A/527F, which is transformation defective. p120 partitioned preferentially with cellular membranes, consistent with the observation that transforming src proteins are membrane associated. Although a number of additional putative substrates were identified and partially characterized with respect to intracellular localization, tyrosine phosphorylation of these proteins was not tightly linked to transformation.

MeSH Terms (13)

Animals Cells, Cultured Genetic Variation Histocytochemistry Molecular Weight Oncogenes Phosphoproteins Phosphorylation Phosphotyrosine Proto-Oncogene Proteins Proto-Oncogene Proteins pp60(c-src) Transformation, Genetic Tyrosine

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