The regulatory region of Prague C v-Src inhibits the activity of the Schmidt-Ruppin A v-Src kinase domain.
Existing variants of the oncogene v-src differ in their transforming potential as well as in the range of their hosts. We compared the protein kinase activities of two Prague C v-Src variants (PRC and H19), reported to be of low oncogenic potential (Plachý et al., 1995), with the highly oncogenic Schmidt-Ruppin A v-Src (SRA). We employed in vitro kinase assays of affinity-purified proteins expressed in rabbit reticulocyte lysate and in S. cerevisiae. In both systems used, the specific kinase activity of the Prague C v-Src kinases amounted to only ca 20% of the activity of SRA. This positions the PRC Src close to activated c-Src, despite the lack of the regulatory C-terminal tail in PRC. We constructed chimeras between PRC and SRA v-Src and tested them for specific kinase activity in S. cerevisiae. Remarkably, the regulatory N-terminal part of PRC, when fused to the SRA-derived kinase domain, lowered the chimeras' PK activity to ca 20%, suggesting that it is the regulatory part of PRC that is responsible for its low phosphotransferase activity.
Brábek
J
J
Department of Physiology, Charles University, Prague, Czech Republic.
Mojzita
D
D
Hamplová
L
L
Folk
P
P
D001358:Avian Sarcoma Viruses / Q000145:classification / Q000201:enzymology* / Q000235:genetics; D020134:Catalytic Domain; D016391:Genes, src; D015688:Oncogene Protein pp60(v-src) / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000494:pharmacology; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000494:pharmacology; D012441:Saccharomyces cerevisiae; D013045:Species Specificity; D013329:Structure-Activity Relationship
D011993:Recombinant Fusion Proteins; D015688:Oncogene Protein pp60(v-src)