Interaction of Protein Kinase C Isozymes with Rho GTPases
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- 作者：Simon J. Slater ; Jodie L. Seiz ; Brigid A. Stagliano ; and Christopher D. Stubbs
- 刊名：Biochemistry
- 出版年：2001
- 出版时间：April 10, 2001
- 年：2001
- 卷：40
- 期：14
- 页码：4437 - 4445
- 全文大小：97K
- 年卷期：v.40,no.14(April 10, 2001)
- ISSN：1520-4995
文摘
Evidence is provided for direct protein-protein interactions between protein kinase C (PKC)
, 
I, II, 
, 
, 
, and 
and members of the Rho family of small GTPases. Previous investigations,based on the immunoprecipitation approach, have provided evidence consistent with a direct interaction,but this remained to be proven. In the study presented here, an in vitro assay, consisting only of purifiedproteins and the requisite PKC activators and cofactors, was used to determine the effects of Rho GTPaseson the activities of the different PKC isoforms. It was found that the activity of PKC was potentlyenhanced by RhoA and Cdc42 and to a lesser extent by Rac1, whereas the effects on the activities ofPKCI, -II, -, -, -, and - were much reduced. These results indicate a direct interaction betweenPKC and each of the Rho GTPases. However, the Rho GTPase concentration dependencies for thepotentiating effects on PKC activity differed for each Rho GTPase and were in the following order:RhoA > Cdc42 > Rac1. PKC was activated in a phorbol ester- and Ca2+-dependent manner. This wasreflected by a substantial decrease in the phorbol ester concentration requirements for activity in thepresence of Ca2+, which for each Rho GTPase was induced within a low nanomolar phorbol esterconcentration range. The activity of PKC also was found to be dependent on the nature of the GTP- orGDP-bound state of the Rho GTPases, suggesting that the interaction may be regulated by conformationalchanges in both PKC and Rho GTPases. Such an interaction could result in significant cross-talk betweenthe distinct pathways regulated by these two signaling elements.
, I, II, , , , and and members of the Rho family of small GTPases. Previous investigations,based on the immunoprecipitation approach, have provided evidence consistent with a direct interaction,but this remained to be proven. In the study presented here, an in vitro assay, consisting only of purifiedproteins and the requisite PKC activators and cofactors, was used to determine the effects of Rho GTPaseson the activities of the different PKC isoforms. It was found that the activity of PKC was potentlyenhanced by RhoA and Cdc42 and to a lesser extent by Rac1, whereas the effects on the activities ofPKCI, -II, -, -, -, and - were much reduced. These results indicate a direct interaction betweenPKC and each of the Rho GTPases. However, the Rho GTPase concentration dependencies for thepotentiating effects on PKC activity differed for each Rho GTPase and were in the following order:RhoA > Cdc42 > Rac1. PKC was activated in a phorbol ester- and Ca2+-dependent manner. This wasreflected by a substantial decrease in the phorbol ester concentration requirements for activity in thepresence of Ca2+, which for each Rho GTPase was induced within a low nanomolar phorbol esterconcentration range. The activity of PKC also was found to be dependent on the nature of the GTP- orGDP-bound state of the Rho GTPases, suggesting that the interaction may be regulated by conformationalchanges in both PKC and Rho GTPases. Such an interaction could result in significant cross-talk betweenthe distinct pathways regulated by these two signaling elements.