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The last 10 amino acid residues beyond the hydrophobic motif are critical for the catalytic competence and function of protein kinase Cá*

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journal contribution
posted on 2006-10-13, 00:00 authored by S Yeong, Y Zhu, D Smith, C Verma, W Lim, B Tan, Q Li, Steve Cheung, M Cai, Y Z Zhu, S F Zhou, S L Tan, Wei DuanWei Duan
The segment C-terminal to the hydrophobic motif at the V5 domain of protein kinase C (PKC) is the least conserved both in length and in amino acid identity among all PKC isozymes. By generating serial truncation mutants followed by biochemical and functional analyses, we show here that the very C terminus of PKCα is critical in conferring the full catalytic competence to the kinase and for transducing signals in cells. Deletion of one C-terminal amino acid residue caused the loss of ~60% of the catalytic activity of the mutant PKCα, whereas deletion of 10 C-terminal amino acid residues abrogated the catalytic activity of PKCα in immune complex kinase assays. The PKCα C-terminal truncation mutants were found to lose their ability to activate mitogen-activated protein kinase, to rescue apoptosis induced by the inhibition of endogenous PKC in COS cells, and to augment melatonin-stimulated neurite outgrowth. Furthermore, molecular dynamics simulations revealed that the deletion of 1 or 10 C-terminal residues results in the deformation of the V5 domain and the ATP-binding pocket, respectively. Finally, PKCα immunoprecipitated using an antibody against its C terminus had only marginal catalytic activity compared with that of the PKCα immunoprecipitated by an antibody against its N terminus. Therefore, the very C-terminal tail of PKCα is a novel determinant of the catalytic activity of PKC and a promising target for selective modulation of PKCα function. Molecules that bind preferentially to the very C terminus of distinct PKC isozymes and suppress their catalytic activity may constitute a new class of selective inhibitors of PKC.

History

Journal

Journal of biological chemistry

Volume

281

Issue

41

Pagination

30768 - 30781

Publisher

American Society for Biochemistry and Molecular Biology

Location

Bethesda, Md

ISSN

0021-9258

eISSN

1083-351X

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2006, American Society for Biochemistry and Molecular Biology, Inc.

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