Protein-tyrosine kinase activity of alternate protein products of the Drosophila Dsrc28C locus.
The Dsrc28C gene is a unique member of the extensive tyrosine kinase family. Two proteins, p66Dsrc28C and p55Dsrc28C, are encoded by the gene. Each contains a highly conserved tyrosine kinase domain and each lacks the usual amino-terminal myristylation signal. The protein-tyrosine kinase activity of the two proteins was investigated through a recombinant baculovirus expression system. p66Dsrc28C expressed from a recombinant baculovirus phosphorylated a large number of Sf9 cell proteins on tyrosine. A group of proteins of approximately 100 kDa were the preferred substrates. No evidence of p66Dsrc28C autophosphorylation was found. In contrast to p66Dsrc28C, p55Dsrc28C did not exhibit protein-tyrosine kinase activity when expressed from a recombinant baculovirus. A deletion derivative of p66Dsrc28C lacking the SH3 and SH2 domains also failed to phosphorylate Sf9 cell proteins. These results suggest that the protein-tyrosine kinase activity of Dsrc28C proteins is tightly regulated.
Theroux
S J
SJ
Cell Biology Group, Worcester Foundation for Experimental Biology, Shrewsbury, MA 01545.
Wadsworth
S C
SC
D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D004330:Drosophila / Q000201:enzymology / Q000235:genetics*; D016391:Genes, src / Q000235:genetics*; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis; D013379:Substrate Specificity
D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D011505:Protein-Tyrosine Kinases