SAP KINASE-3, A NEW MEMBER OF THE FAMILY OF MAMMALIAN STRESS-ACTIVATED PROTEIN-KINASES

Stress-activated protein kinases are MAP kinase homologues that are ac tivated by cellular stresses, bacterial endotoxin and inflammatory cyt okines, They are activated by a dual threonine/tyrosine phosphorylatio n within a TPY sequence in the case of stress-activated protein kinase -1 and its isoforms (also called JNKs) or a TGY sequence in the case o f stress-activated protein kinase-2 and its isoforms (also called p38, p40, RK, CSBPs, XMpk2 and Mxi2), Here we report the cloning and seque ncing of a new protein kinase from rat with a TGY sequence in the acti vation domain, This stress-activated protein kinase-3 is 60% identical to mouse stress-activated protein kinase-2 and 45% identical to HOG1 from Saccharomyces cerevisiae. Transcripts encoding stress-activated p rotein kinase-3 are widely expressed, with high levels in skeletal mus cle.