Regulation of Dynamin I GTPase Activity by G Protein βγ Subunits and Phosphatidylinositol 4,5-Bisphosphate

doi:10.1074/jbc.271.45.27979

Regulation of Dynamin I GTPase Activity by G Protein βγ Subunits and Phosphatidylinositol 4,5-Bisphosphate*

Hsin Chieh Lin and
Alfred G. Gilman^‡

From the Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75235

^‡ To whom correspondence should be addressed:
Dept. of Pharmacology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75235.

Abstract

Dynamin I is a 100-kDa GTPase that plays an important role in the recycling of synaptic vesicles. Hydrolysis of GTP by dynamin is thought to be a critical step in fission of coated pits to form coated vesicles. We report that the heterotrimeric G protein βγ subunit complex (G_βγ) and phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P₂) are negative and positive regulators of dynamin GTPase activity, respectively. Furthermore, the apparent affinity of dynamin for G_βγ is substantially enhanced by PtdIns(4,5)P₂. However, the GTPase activity of oligomeric dynamin is unaffected by G_βγ. The effects of heterotrimeric G proteins on endocytosis may thus be mediated directly and not involve more remote aspects of their signaling properties.

Footnotes

↵* This work was supported by National Institutes of Health Grant GM 34497 and the Raymond and Ellen Willie Distinguished Chair in Molecular Neuropharmacology. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ J. P. Albanesi and J. F. Eccleston, personal communication.
↵² The abbreviations used are:

PH

pleckstrin homology

GSTαA

glutathione S-transferase-α-adaptin

G protein

heterotrimeric guanine nucleotide-binding protein

PtdIns(4,5)P₂

phosphatidylinositol-4,5-bisphosphate

DTT

dithiothreitol

PAGE

polyacrylamide gel electrophoresis

GTPγS

guanosine 5′-3-O-(thio)triphosphate.
- Received August 28, 1996.
- Revision received September 19, 1996.