Cloning and characterization of a novel serine/threonine protein kinase gene expressed predominantly in developing brain

We have isolated a rat gene, sbk, that encodes a novel serine/threonine pro tein kinase possessing a consensus sequence for an SH3-binding domain from developing rat brain. Rat SBK comprises 417 amino-acid residues consisting of a serine/threonine protein kinase consensus sequence followed by a C-ter minal proline-rich region. Sequence comparison with other known kinases rev ealed that sbk belongs to a novel family of serine/threonine protein kinase s structurally related to a Xenopus gastrula-specific protein kinase, Pk9.7 . An in vitro kinase assay demonstrated that the SBK protein autophosphoryl ates at serine/threonine residues. Transcripts of sbk were strongly detecte d in brain, and the distribution shows an association with neurons but not glial cells. A marked increase in sbk transcripts was observed in developin g brain in the late embryonic stage when dramatic neuronal proliferation, m igration, and maturation occur. Fluorescence in situ hybridization analysis was used to map sbk to mouse chromosome 7F1-F3 and rat chromosome 1q21. Th ese data suggest a role for SBK in signal-transduction pathways related to the control of brain development.