[Characterization of a putative S locus encoded receptor protein kinase and its role in self-incompatibility]. Progress report, January 1993
The serine/threonine protein kinase (SRK) protein was predicted to be similar to the growth factor receptor tyrosine kinases in animals but its amino acid sequence of the catalytic domain is more similar to that of the catalytic domains of protein serine/threonine kinases than to protein tyrosine kinases. We have shown that the SRK protein has intrinsic scrine/threonine kinase activity. We subcloned the protein kinase-homologous domain of the SRK{sub 6} cDNA into the bacterial expression vector pGEX-3X and we have constructed a second plasmid identical to the first except that it carried a conservative mutation that substituted Arg for the Lys{sup 524} codon of SRK6 This lysine corresponds to the ATP-binding site, is essential in protein kinases, and is a common target for site-directed mutagenesis as a means to obtain kinase-defective proteins. Cultures bearing the wild-type and mutant SRK catalytic domains each produced an approximately 64 kD protein that reacted with anti-SRK6 antibodies. Following pulse-labeling with {sup 32}P we found that the wild-type SRK6 protein but not the mutant form was detectably phosphorylated. Phosphoamino acid analysis of the affinity purified {sup 32}p-labeled GST-SRK6 fusion protein demonstrated that SRK was phosphorylated predominantly on semine and to a lesser extent on threonine, but not on tyrosine. Thus, SRK6 is a functional serine/threonine protein kinase.
- Research Organization:
- Cornell Univ., Ithaca, NY (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-88ER13909
- OSTI ID:
- 10152477
- Report Number(s):
- DOE/ER/13909-3; ON: DE93013987
- Resource Relation:
- Other Information: PBD: 1993
- Country of Publication:
- United States
- Language:
- English
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