Retinoic Acid Binds to the C2-Domain of Protein Kinase C
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- 作者：Wendy F. Ochoa ; Alejandro Torrecillas ; Ignacio Fita ; Nuria Verdaguer ; Senena Corbalá ; n-Garcí ; a ; and Juan C. Gomez-Fernandez
- 刊名：Biochemistry
- 出版年：2003
- 出版时间：July 29, 2003
- 年：2003
- 卷：42
- 期：29
- 页码：8774 - 8779
- 全文大小：473K
- 年卷期：v.42,no.29(July 29, 2003)
- ISSN：1520-4995
文摘
Protein kinase C
(PKC) 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. Crystalsof the C2-domain of PKC, 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 previouslyreported for acidic phospholipids. The first binding site corresponds to the Ca2+-binding pocket, whereCa2+ ions mediate the interactions of atRA with the protein, as they do with acidic phospholipids. Thesecond binding site corresponds to the conserved lysine-rich cluster localized in 
-strands three and four.These observations are strongly supported by [3H]-atRA-binding experiments combined with site-directedmutagenesis. Wild-type C2-domain binds 2 mol of atRA per mol of protein, while the rate reduces to onein the case of C2-domain variants, in which mutations affect either Ca2+ coordination or the integrity ofthe lysine-rich cluster site. Competition between atRA and acidic phospholipids to bind to PKC is apossible mechanism for modulating PKC activity.
(PKC) 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. Crystalsof the C2-domain of PKC, 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 previouslyreported for acidic phospholipids. The first binding site corresponds to the Ca2+-binding pocket, whereCa2+ ions mediate the interactions of atRA with the protein, as they do with acidic phospholipids. Thesecond binding site corresponds to the conserved lysine-rich cluster localized in -strands three and four.These observations are strongly supported by [3H]-atRA-binding experiments combined with site-directedmutagenesis. Wild-type C2-domain binds 2 mol of atRA per mol of protein, while the rate reduces to onein the case of C2-domain variants, in which mutations affect either Ca2+ coordination or the integrity ofthe lysine-rich cluster site. Competition between atRA and acidic phospholipids to bind to PKC is apossible mechanism for modulating PKC activity.