Article Abstract:
Cdk7 is known to be capable of phosphorylating and activating many different Cdks in vitro. The Drosophila cdk7 homolog has been cloned. Null and temperature-sensitive mutations have been created. For CAK activity in vivo in a multicellular organism cdk7 is needed and its activity is required for activation of both Cdc2/Cyclin A and Cdc/Cyclin B complexes, and for cell division. Bringing about a key modification of Cdks may be fundamentally different in metazoans and budding yeasts. Cyclin is needed for mitosis and for in Cdk-activating kinase activity in vivo.
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Article Abstract:
The protein Cdk7 has a role in CAK function, although the Cdk subunit alone is inactive. It must work with a cyclin and with phosphorylation on a conserved threonine residue to be entirely activated. Activity in the presence of those factors is greater by seven orders of magnitude. Cdk regulatory mechanisms ultimately control cell cycle transitions and proliferations. It is necessary to know why Cdk function evolved to require CAK activation to completely understand CAK biology.
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Article Abstract:
Research indicates that the SCF(beta-TRCP) complex plays a key role in intracellular processes. Experiments determined that the complex recognizes destruction motifs, including a 19-amino-acid destruction motif in I(kappa)B(alpha) residues 21 through 41 and a conserved destruction motif for beta-catenin. The experiments also showed cofractionation of SCF(beta-TRCP) with I(kappa)B(alpha)-ubiquitin ligase activity.
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