![]() ![]() It also suggested a link between the seemingly unrelated events of CTD phosphorylation and CDK activation, which was an unexpected and to this day controversial notion. This discovery ended the search for the protein kinase associated with this general transcription factor, which was known to phosphorylate the CTD in vitro ( Feaver et al., 1991 Lu et al., 1992 Serizawa et al., 1992). First, CDK7, cyclin H and a third subunit, the RING finger protein MAT1, were found to be associated with TFIIH ( Roy et al., 1994 Fisher et al., 1995 Serizawa et al., 1995 Shiekhattar et al., 1995), as was the budding yeast ortholog of CDK7, Kin28 ( Feaver et al., 1994). This connection might help to ensure that mRNAs encoding effectors of cell division are expressed at the right time in the cycle.Īlmost immediately, the identity of CAK and the function of CDK7 in vivo were called into question by two independent discoveries. Finally, despite divergence in their wiring, the CAK-CDK networks of budding yeast, fission yeast and metazoans all link transcriptional regulation with operation of the cell-cycle machinery. First, how does CDK7 achieve the dual substrate specificity necessary to perform both roles? Second, is there a deeper connection implied by the dichotomy of CDK7 function, for example similar mechanisms controlling cell division and gene expression, and/or actual coordination of the two processes? Enzymological studies have revealed solutions to the unusual substrate recognition problem, and there is evidence that the distinct functions of CDK7 can be regulated independently. ![]() Controversy over its double duty has been resolved, but questions remain. ![]() In metazoans, cyclin-dependent kinase 7 (CDK7) has essential roles in both the cell-division cycle and transcription, as a CDK-activating kinase (CAK) and as a component of the general transcription factor TFIIH, respectively. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |