Sat, 26 Jul 2008 07:46:55 BST CiteULike: neils's arginine http://www.citeulike.org/user/neils/tag/arginine CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/neils/article/2054425 <i>J Biol Chem, Vol. 279, No. 6. (Feb 2004), pp. 4612-4624.</i><br /><br />A novel method employing filter arrays of a cDNA expression library for the identification of substrates for protein kinases was developed. With this technique, we identified a new member of the cyclin family, cyclin L2, as a substrate of the nuclear protein kinase DYRK1A. Cyclin L2 contains an N-terminal cyclin domain and a C-terminal arginine/serine-rich domain (RS domain), which is a hallmark of many proteins involved in pre-mRNA processing. The gene for cyclin L2 encodes the full-length cyclin L2, which is predominantly expressed in testis, as well as a truncated splicing variant (cyclin L2S) that lacks the RS domain and is ubiquitously expressed in human tissues. Full-length cyclin L2, but not cyclin L2S, was associated with the cyclin-dependent kinase PITSLRE. Cyclin L2 interacted with splicing factor 2 in vitro and was co-localized with the splicing factor SC35 in the nuclear speckle compartment. Photobleaching experiments showed that a fusion protein of green fluorescent protein and cyclin L2 in nuclear speckles rapidly exchanged with unbleached molecules in the nucleus, similar to other RS domain-containing proteins. In striking contrast, the closely related green fluorescent protein-cyclin L1 was immobile in the speckle compartment. DYRK1A interacted with cyclin L2 in pull-down assays, and overexpression of DYRK1A stimulated phosphorylation of cyclin L2 in COS-7 cells. These data characterize cyclin L2 as a highly mobile component of nuclear speckles and suggest that DYRK1A may regulate splicing by phosphorylation of cyclin L2. Characterization of cyclin L2, a novel cyclin with an arginine/serine-rich domain: phosphorylation by DYRK1A and colocalization with splicing factors. Katrin de Graaf Paul Hekerman Oliver Spelten Andreas Herrmann Len Packman Konrad Büssow Gerhard Newen Walter Becker J Biol Chem, Vol. 279, No. 6. (Feb 2004), pp. 4612-4624. 2007-12-04T03:22:09-00:00 2004 J Biol Chem 279 6 4612 4624 amino-acid animal arginine article-predikin base cell complementary cos cyclin data dna factors fusion human kinase male mice molecular nucleus phosphorylation protein protein-serine-threonine protein-tyrosine rat recombinant rna sequence serine specificity splicing structure substrate tertiary transcription