Thu, 21 Aug 2008 14:07:28 BST CiteULike: neils's base http://www.citeulike.org/user/neils/tag/base CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/neils/article/2287238 <i>J Mol Evol, Vol. 44, No. 6. (June 1997), pp. 632-636.</i><br /><br />G:C pairs are more stable than A:T pairs because they have an additional hydrogen bond. This has led to many studies on the correlation between the guanine+cytosine (G+C) content of nucleic acids and temperature over the last 20 years. We collected the optimal growth temperatures (Topt) and the G+C contents of genomic DNA; 23S, 16S, and 5S ribosomal RNAs; and transfer RNAs for 764 prokaryotic species. No correlation was found between genomic G+C content and Topt, but there were striking correlations between the G+C content of ribosomal and transfer RNA stems and Topt. Two explanations have been proposed-neutral evolution and selection pressure-for the approximate equalities of G and C (respectively, A and T) contents within each strand of DNA molecules. Our results do not support the notion that selection pressure induces complementary oligonucleotides in close proximity and therefore numerous secondary structures in prokaryotic DNA, as the genomic G+C content does not behave in the same way as that of folded RNA with respect to optimal growth temperature. Relationships between genomic G+C content, RNA secondary structures, and optimal growth temperature in prokaryotes. N Galtier JR Lobry J Mol Evol, Vol. 44, No. 6. (June 1997), pp. 632-636. 2008-01-25T06:29:20-00:00 1997 J Mol Evol 0022-2844 44 6 632 636 base composition dna for-thuber genomics ogt prokaryote rna thermal 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