Competitive Binding of Protein Kinase C to Membranes and Rho GTPases
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- 作者：Anthony C. Cook ; Cojen Ho ; Jennifer L. Kershner ; Steve A. Malinowski ; Heath Moldveen ; Brigid A. Stagliano ; Simon J. Slater
- 刊名：Biochemistry
- 出版年：2006
- 出版时间：December 5, 2006
- 年：2006
- 卷：45
- 期：48
- 页码：14452 - 14465
- 全文大小：254K
- 年卷期：v.45,no.48(December 5, 2006)
- ISSN：1520-4995
文摘
Previously, we have shown that protein kinase C
(PKC) forms a direct high-affinity, isozyme-specific and membrane lipid-independent interaction with Rho GTPases [Slater, S. J., Seiz, J. L., Stagliano,B. A., and Stubbs, C. D. (2001) Biochemistry 40, 4437-4445]. Since the cellular activation of PKCinvolves an initial translocation from cytosolic to membrane compartments, the present study investigatesthe interdependence between the direct protein-protein interaction of PKC with the Rho GTPase, Cdc42,and the protein-lipid interactions of PKC with membranes. It was hypothesized that the interaction ofPKC with membrane-bound Cdc42 would contribute to the overall membrane-binding affinity of thekinase by providing an additional anchor. However, it was found that the incorporation of isoprenylatedCdc42 into membranes resulted in an apparent decrease in the membrane-binding affinity of PKC, whereasthe association of PKC
I, PKC
, PKC
, and PKC
was each unaffected. The presence of membrane-bound Cdc42 resulted in a rightward shift in both the PS- and Ca2+-concentration response curves forPKC membrane association and for the ensuing activation, whereas the maximal levels of binding andactivation attained at saturating PS and Ca2+ concentrations were in each case unaffected. Overall, thesefindings suggest that PKC undergoes a isozyme-specific interaction with membrane-bound Cdc42 toform a PKC-Cdc42 complex, which possesses a membrane-binding affinity that is reduced relative tothat of the individual components due to competition between Cdc42 and PS/Ca2+ for binding to PKC.Consistent with this, it was found that the interaction of PKC with membrane-bound Cdc42 wasaccompanied by the physical dissociation of the PKC-Cdc42 complex from membranes. Thus, thestudy provides a novel mechanism by which the membrane association and activation of PKC and Cdc42may be regulated by competing protein-protein and protein-lipid interactions.
(PKC) forms a direct high-affinity, isozyme-specific and membrane lipid-independent interaction with Rho GTPases [Slater, S. J., Seiz, J. L., Stagliano,B. A., and Stubbs, C. D. (2001) Biochemistry 40, 4437-4445]. Since the cellular activation of PKCinvolves an initial translocation from cytosolic to membrane compartments, the present study investigatesthe interdependence between the direct protein-protein interaction of PKC with the Rho GTPase, Cdc42,and the protein-lipid interactions of PKC with membranes. It was hypothesized that the interaction ofPKC with membrane-bound Cdc42 would contribute to the overall membrane-binding affinity of thekinase by providing an additional anchor. However, it was found that the incorporation of isoprenylatedCdc42 into membranes resulted in an apparent decrease in the membrane-binding affinity of PKC, whereasthe association of PKCI, PKC, PKC, and PKC was each unaffected. The presence of membrane-bound Cdc42 resulted in a rightward shift in both the PS- and Ca2+-concentration response curves forPKC membrane association and for the ensuing activation, whereas the maximal levels of binding andactivation attained at saturating PS and Ca2+ concentrations were in each case unaffected. Overall, thesefindings suggest that PKC undergoes a isozyme-specific interaction with membrane-bound Cdc42 toform a PKC-Cdc42 complex, which possesses a membrane-binding affinity that is reduced relative tothat of the individual components due to competition between Cdc42 and PS/Ca2+ for binding to PKC.Consistent with this, it was found that the interaction of PKC with membrane-bound Cdc42 wasaccompanied by the physical dissociation of the PKC-Cdc42 complex from membranes. Thus, thestudy provides a novel mechanism by which the membrane association and activation of PKC and Cdc42may be regulated by competing protein-protein and protein-lipid interactions.