Retinoic Acid Binds to the C2-Domain of Protein Kinase Cα
Protein kinase Cα (PKCα) is a key enzyme regulating the physiology of cells and their growth, differentiation, and apoptosis. PKC activity is known to be modulated by all-trans retinoic acid (atRA), although neither the action mechanism nor even the possible binding to PKCs has been established. Cry...
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Published in | Biochemistry (Easton) Vol. 42; no. 29; pp. 8774 - 8779 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
American Chemical Society
29.07.2003
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Online Access | Get full text |
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Summary: | Protein kinase Cα (PKCα) is a key enzyme regulating the physiology of cells and their growth, differentiation, and apoptosis. PKC activity is known to be modulated by all-trans retinoic acid (atRA), although neither the action mechanism nor even the possible binding to PKCs has been established. Crystals of the C2-domain of PKCα, a regulatory module in the protein that binds Ca2+ and acidic phospholipids, have now been obtained by cocrystallization with atRA. The crystal structure, refined at 2.0 Å resolution, shows that RA binds to the C2-domain in two locations coincident with the two binding sites previously reported for acidic phospholipids. The first binding site corresponds to the Ca2+-binding pocket, where Ca2+ ions mediate the interactions of atRA with the protein, as they do with acidic phospholipids. The second binding site corresponds to the conserved lysine-rich cluster localized in β-strands three and four. These observations are strongly supported by [3H]-atRA-binding experiments combined with site-directed mutagenesis. Wild-type C2-domain binds 2 mol of atRA per mol of protein, while the rate reduces to one in the case of C2-domain variants, in which mutations affect either Ca2+ coordination or the integrity of the lysine-rich cluster site. Competition between atRA and acidic phospholipids to bind to PKC is a possible mechanism for modulating PKCα activity. |
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Bibliography: | ark:/67375/TPS-D59NSBTF-3 This work was supported by the following grants to (a) J.C.G.F. (Universidad de Murcia): BMC2002-00119 from Dirección General de Investigación, Ministerio de Ciencia y Tecnología (Spain) and PI-35/00789/FS/01 from Fundación Séneca (Comunidad Autónoma de Murcia, Spain) and (b) I.F. (Barcelona): BIO099-0865 (Spain). istex:28FB04F7C623CC52E5603414124E91A1E040B77A |
ISSN: | 0006-2960 1520-4995 |
DOI: | 10.1021/bi034713g |