Low- and High-Affinity Phorbol Ester and Diglyceride Interactions with Protein Kinase C: 1-O-Alkyl-2-acyl-sn-glycerol Enhances Phorbol Ester- and Diacylglycerol-Induced Activity but Alon
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- 作者：Simon J. Slater ; Jodie L. Seiz ; Brigid A. Stagliano ; Anthony C. Cook ; Shawn K. Milano ; Cojen Ho ; and Christopher D. Stubbs
- 刊名：Biochemistry
- 出版年：2001
- 出版时间：May 22, 2001
- 年：2001
- 卷：40
- 期：20
- 页码：6085 - 6092
- 全文大小：90K
- 年卷期：v.40,no.20(May 22, 2001)
- ISSN：1520-4995
文摘
Phorbol ester-induced conventional protein kinase C (PKC
, -
/, and -
) isozyme activitiesare potentiated by 1,2-diacyl-sn-glycerol. This has been attributed to a "cooperative" interaction of thetwo activators with two discrete sites termed the low- and high-affinity phorbol ester binding sites,respectively [Slater, S. J., Milano, S. K., Stagliano, B. A., Gergich, K. J., Ho, C., Mazurek, A., Taddeo,F. J., Kelly, M. B., Yeager, M. D., and Stubbs, C. D. (1999) Biochemistry 38, 3804-3815]. Here, wereport that the 1-O-alkyl ether diglyceride, 1-O-hexadecyl-2-acetyl-sn-glycerol (HAG), like its 1,2-diacylcounterpart, 1-oleoyl-2-acetyl-sn-glycerol (OAG), also potentiated PKC, -I/II, and - activities inducedby the phorbol ester 4-12-O-tetradecanoylphorbol-13-acetate (TPA). Similar to OAG, HAG was foundto bind to the low-affinity phorbol ester binding site and to enhance high-affinity phorbol ester binding,and to decrease the level of Ca2+ required for phorbol ester-induced activity, while being without effecton the Ca2+ dependence of membrane association. Thus, similar to OAG, HAG may also potentiate phorbolester-induced activity by interacting with the low-affinity phorbol ester binding site, leading to a reducedlevel of Ca2+ required for the activating conformational change. However, HAG was found not to behavelike a 1,2-diacyl-sn-glycerol in that alone it did not induce PKC activity, and also in that it enhancedOAG-induced activity. The results reveal HAG to be a member of a new class of "nonactivating"compounds that modulate PKC activity by interacting with the low-affinity phorbol ester binding site.
, -/, and -) isozyme activitiesare potentiated by 1,2-diacyl-sn-glycerol. This has been attributed to a "cooperative" interaction of thetwo activators with two discrete sites termed the low- and high-affinity phorbol ester binding sites,respectively [Slater, S. J., Milano, S. K., Stagliano, B. A., Gergich, K. J., Ho, C., Mazurek, A., Taddeo,F. J., Kelly, M. B., Yeager, M. D., and Stubbs, C. D. (1999) Biochemistry 38, 3804-3815]. Here, wereport that the 1-O-alkyl ether diglyceride, 1-O-hexadecyl-2-acetyl-sn-glycerol (HAG), like its 1,2-diacylcounterpart, 1-oleoyl-2-acetyl-sn-glycerol (OAG), also potentiated PKC, -I/II, and - activities inducedby the phorbol ester 4-12-O-tetradecanoylphorbol-13-acetate (TPA). Similar to OAG, HAG was foundto bind to the low-affinity phorbol ester binding site and to enhance high-affinity phorbol ester binding,and to decrease the level of Ca2+ required for phorbol ester-induced activity, while being without effecton the Ca2+ dependence of membrane association. Thus, similar to OAG, HAG may also potentiate phorbolester-induced activity by interacting with the low-affinity phorbol ester binding site, leading to a reducedlevel of Ca2+ required for the activating conformational change. However, HAG was found not to behavelike a 1,2-diacyl-sn-glycerol in that alone it did not induce PKC activity, and also in that it enhancedOAG-induced activity. The results reveal HAG to be a member of a new class of "nonactivating"compounds that modulate PKC activity by interacting with the low-affinity phorbol ester binding site.