Physical and Functional Interaction of Rabphilin-3A with α-Actinin

doi:10.1074/jbc.271.50.31775

Physical and Functional Interaction of Rabphilin-3A with α-Actinin*

From the ^¶ Department of Molecular Biology and Biochemistry, Osaka University Medical School, Suita 565,
^″ Takai Biotimer Project, ERATO, Japan Science and Technology Cooperation, Kobe 651-22, and the
^‴ Department of Cell Biology, National Institute of Neuroscience, NCNP, Kodaira 187, Japan

^† To whom correspondence should be addressed:
Dept. of Molecular Biology and Biochemistry, Osaka University Medical School, Suita 565, Osaka, Japan.
Tel.: 81-6-879-3410; Fax: 81-6-879-3419; E-mail: ytakai{at}molbio.med.osaka-u.ac.jp

↵^∥ Present address: The Third Dept. of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka 812-82, Japan.

Abstract

Rabphilin-3A is a downstream target molecule of Rab3A small GTP-binding protein and implicated in Ca²⁺-dependent neurotransmitter release. Here we have isolated a rabphilin-3A-interacting molecule from a human brain cDNA library by the yeast two-hybrid method and identified it to be α-actinin, known to cross-link actin filaments into a bundle. α-Actinin interacts with the N-terminal region of rabphilin-3A, with which GTP-Rab3A interacts, and this interaction stimulates the activity of α-actinin to cross-link actin filaments into a bundle. The interaction of rabphilin-3A with α-actinin is inhibited by guanosine 5′-(3-O-thio)triphosphate-Rab3A. These results suggest that the Rab3A-rabphilin-3A system regulates the α-actinin-regulated reorganization of actin filaments. It has been shown that reorganization of actin filaments is also involved in Ca²⁺-dependent exocytosis. Therefore, rabphilin-3A may serve as a linker for Rab3A and cytoskeleton.

Footnotes

↵* The work at Osaka University Medical School was supported by grants-in-aid for Scientific Research and for Cancer Research from the Ministry of Education, Science, Sports, and Culture, Japan (1996), by grants-in-aid for Abnormalities in Hormone Receptor Mechanisms and for Aging and Health from the Ministry of Health and Welfare, Japan (1996), and by grants from the Human Frontier Science Program (1996) and the Uehara Memorial Foundation (1996). 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.
↵² The abbreviations used are:

SNARE

SNAP receptor

NSF

N-ethylmaleimide-sensitive fusion protein

SNAP

soluble NSF attachment protein

AP2

clathrin adaptor complex-2

IP4

inositol 1,3,4,5-tetrakisphosphate

GTPγS

guanosine 5′-3-O-(thio)triphosphate

aa

amino acids

HA

hemagglutinin

CHAPS

3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid

PAGE

polyacrylamide gel electrophoresis.
↵¹ M. E. Burns, T. Sasaki, Y. Takai, and G. Augustine, manuscript in preparation.
↵³ M. Imamura, manuscript in preparation.
↵⁴ H. Nishioka and Y. Takai, unpublished observations.
- Received August 13, 1996.
- Revision received October 7, 1996.