NCBI Summary:
The protein encoded by this gene is a member of the serine/threonine kinase family. This kinase contains a SH3 domain and a leucine zipper-basic motif. This kinase preferentially activates MAPK8/JNK kinase, and functions as a positive regulator of JNK signaling pathway. This kinase can directly phosphorylate, and activates IkappaB kinase alpha and beta, and is found to be involved in the transcription activity of NF-kappaB mediated by Rho family GTPases and CDC42. [provided by RefSeq, Jul 2008]
General function
Chromosome organization, Enzyme
Comment
Cellular localization
Nuclear
Comment
Ovarian function
Comment
The conserved kinase SRPK regulates karyosome formation and spindle microtubule assembly in Drosophila oocytes. Loh BJ et al. In Drosophila oocytes, after the completion of recombination, meiotic chromosomes form a compact cluster called the karyosome within the nucleus, and later assemble spindle microtubules without centrosomes. Although these oocyte specific phenomena are also observed in humans, their molecular basis is not well understood. Here we report essential roles for the conserved kinase SRPK in both karyosome formation and spindle microtubule assembly in oocytes. We have identified a female sterile srpk mutant through a cytological screen for karyosome defects. Unlike most karyosome mutants, the karyosome defect is independent of the meiotic recombination checkpoint. Heterochromatin clustering found within the wild-type karyosome is disrupted in the mutant. Strikingly, a loss of SRPK severely prevents microtubule assembly for acentrosomal spindles in mature oocytes. Subsequently, bi-orientation and segregation of meiotic chromosomes are also defective. Therefore, this study demonstrates new roles of this conserved kinase in two independent meiotic steps specific to oocytes.