MOLECULAR-CLONING AND CHARACTERIZATION OF A NOVEL PUTATIVE STE20-LIKEKINASE IN GUINEA-PIGS

Protein kinases play a key role in cell growth and differentiation. We have isolated the cDNA of a novel protein serine/threonine kinase (re ferred to as STE20-like kinase (SLK)) from a guinea pig liver cDNA lib rary with a probe generated by a cloning approach based on the polymer ase chain reaction. The encoded polypeptide (1231 amino acids, M-r 141 ,079) contains all conserved subdomains characteristic of the protein serine threonine kinase family. A hemagglutinin-tagged SLK expressed a rtificially in COS7 cells was hyperphosphorylated by anisomycin. By No rthern blot analysis, SLK mRNA was detected in all organs examined: br ain, lung heart, liver, kidney, spleen, testis, and eosinophils. Seque nce comparisons of its catalytic domain related SLK to p21-activated k inase family of protein serine/threonine kinases, Its noncatalytic dom ain comprises several intriguing structural features, including the ac idic region and the nuclear targeting sequence. This noncatalytic doma in exhibited no extended similarity with other proteins. Thus, SLK is a protein serine/threonine kinase which contains an unknown regulatory domain(s). (C) 1997 Academic Press.