Suppression of c-Src activity by C-terminal Src kinase involves the c-Src SH2 and SH3 domains: analysis with Saccharomyces cerevisiae.
The kinase activity of c-Src is normally repressed in vertebrate cells by extensive phosphorylation of Y-527. C-terminal Src kinase (CSK) is a candidate for the enzyme that catalyzes this phosphorylation. We have used budding yeast to study the regulation of c-Src activity by CSK in intact cells. Expression of c-Src in Saccharomyces cerevisiae, which lacks endogenous c-Src and Y-527 kinases, induces a kinase-dependent growth inhibition. Coexpression of CSK in these cells results in phosphorylation of c-Src on Y-527 and suppression of the c-Src phenotype. CSK does not fully suppress the activity of c-Src mutants lacking portions of the SH2 or SH3 domains, even though these mutant proteins are phosphorylated on Y-527 by CSK both in vivo and in vitro. These results suggest that both the SH2 and SH3 domains of c-Src are required for the suppression of c-Src activity by Y-527 phosphorylation.
Murphy
S M
SM
Department of Physiology, University of California, San Francisco 94143-0444.
Bergman
M
M
Morgan
D O
DO
D000081247:CSK Tyrosine-Protein Kinase; D002455:Cell Division; D004252:DNA Mutational Analysis; D015688:Oncogene Protein pp60(v-src) / Q000378:metabolism*; D010641:Phenotype; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D013329:Structure-Activity Relationship; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism; D019061:src-Family Kinases
D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; D019000:Phosphotyrosine; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D015688:Oncogene Protein pp60(v-src); D016392:Proto-Oncogene Proteins pp60(c-src); D019061:src-Family Kinases