Identification of a common protein association region in the neuronal Cdk5 activator.
Cyclin-dependent protein kinase 5 (Cdk5) depends on the association with neuronal Cdk5 activator (Nck5a) for kinase activity. A variety of cellular proteins have been shown to undergo high affinity association with Nck5a, including three novel proteins, C42, C48, and C53 found by a yeast two-hybrid screen (Ching, Y. P., Qi, Z., and Wang, J. H. (2000) Gene 242, 285-294). The three proteins show competitive binding to Nck5a suggesting that they bind at a common site. The binding site has been mapped to a region of 26 amino acid residues (residues 145 to 170) at the N-terminal boundary of the kinase activation domain of Nck5a. This region of Nck5a contains an amphipathic alpha-helix whose hydrophobic face is involved in Cdk5 activation (Chin, K. T., Ohki, S, Tang, D., Cheng, H. C., Wang, J. H. , and Zhang, M. (1999) J. Biol. Chem. 274, 7120-7127). Several lines of evidence suggest that Nck5a interacts with the binding proteins at the hydrophilic face of the amphipathic alpha-helix. First, the Nck5a-(145-170) peptide can bind Cdk5 and Nck5a-binding proteins simultaneously. Second, the association of Nck5a-(145-170) to C48 can be markedly reduced by high ionic strength whereas the interaction between Nck5a and Cdk5 is not affected. Third, substitution of Glu(157) by glutamine in Nck5a-(145-170) abolishes the peptide's ability to bind to the three Nck5a-binding proteins without diminishing its Cdk5 binding activity.
Department of Biochemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, Peoples Republic of China.
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D019943:Amino Acid Substitution / Q000235:genetics; D001667:Binding, Competitive; D002352:Carrier Proteins / Q000378:metabolism*; D018797:Cell Cycle Proteins; D051360:Cyclin-Dependent Kinase 5; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D046911:Macromolecular Substances; D009154:Mutation / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D009994:Osmolar Concentration; D010446:Peptide Fragments / Q000378:metabolism; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D025521:Tumor Suppressor Proteins; D019885:Sulfur Group Transferases; D024101:Mitochondrial Proteins
D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D051360:Cyclin-Dependent Kinase 5; D018844:Cyclin-Dependent Kinases; D047908:Intracellular Signaling Peptides and Proteins; D046911:Macromolecular Substances; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D025521:Tumor Suppressor Proteins; C405929:CDK5RAP2 protein, human; C405928:CDK5RAP3 protein, human; C089495:neuronal Cdk5 activator (p25-p35); C495905:CDK5 protein, human; C405930:CDK5RAP1 protein, human; D019885:Sulfur Group Transferases; D024101:Mitochondrial Proteins