RACK1 regulates specific functions of Gbetagamma.

Chen S, Dell EJ, Lin F, Sai J, Hamm HE
J Biol Chem. 2004 279 (17): 17861-8

PMID: 14963031 · DOI:10.1074/jbc.M313727200

We showed previously that Gbetagamma interacts with Receptor for Activated C Kinase 1 (RACK1), a protein that not only binds activated protein kinase C (PKC) but also serves as an adaptor/scaffold for many signaling pathways. Here we report that RACK1 does not interact with Galpha subunits or heterotrimeric G proteins but binds free Gbetagamma subunits released from activated heterotrimeric G proteins following the activation of their cognate receptors in vivo. The association with Gbetagamma promotes the translocation of RACK1 from the cytosol to the membrane. Moreover, binding of RACK1 to Gbetagamma results in inhibition of Gbetagamma-mediated activation of phospholipase C beta2 and adenylyl cyclase II. However, RACK1 has no effect on other functions of Gbetagamma, such as activation of the mitogen-activated protein kinase signaling pathway or chemotaxis of HEK293 cells via the chemokine receptor CXCR2. Similarly, RACK1 does not affect signal transduction through the Galpha subunits of G(i), G(s), or G(q). Collectively, these findings suggest a role of RACK1 in regulating specific functions of Gbetagamma.

MeSH Terms (33)

Adenylyl Cyclases Animals Cell Line Cell Membrane Chemotaxis COS Cells Cyclic AMP Cytosol Dimerization Dose-Response Relationship, Drug Enzyme Activation Gene Expression Regulation Glutathione Transferase GTP-Binding Protein beta Subunits GTP-Binding Protein gamma Subunits GTP-Binding Proteins Humans Hydrolysis Interleukin-8 Isoenzymes Lipid Metabolism MAP Kinase Signaling System Microscopy, Confocal Microscopy, Fluorescence Neoplasm Proteins Phospholipase C beta Protein Binding Protein Transport Receptors, Cell Surface Receptors for Activated C Kinase Signal Transduction Transfection Type C Phospholipases

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