Physical and functional interaction of rabphilin-3A with alpha-actinin.
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 alpha-actinin, known to cross-link actin filaments into a bundle. alpha-Actinin interacts with the N-terminal region of rabphilin-3A, with which GTP-Rab3A interacts, and this interaction stimulates the activity of alpha-actinin to cross-link actin filaments into a bundle. The interaction of rabphilin-3A with alpha-actinin is inhibited by guanosine 5'-(3-O-thio)triphosphate-Rab3A. These results suggest that the Rab3A-rabphilin-3A system regulates the alpha-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.
Kato
M
M
Department of Molecular Biology and Biochemistry, Osaka University Medical School, Suita 565, Osaka, Japan. ytakai@molbio.med.osaka-u.ac.jp
Sasaki
T
T
Ohya
T
T
Nakanishi
H
H
Nishioka
H
H
Imamura
M
M
Takai
Y
Y
D000185:Actinin / Q000737:chemistry / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D016716:PC12 Cells; D051381:Rats; D018411:Spodoptera; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins; D000097624:Rabphilin-3A
D000185:Actinin; D048868:Adaptor Proteins, Signal Transducing; D019204:GTP-Binding Proteins; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D009419:Nerve Tissue Proteins; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins; D000097624:Rabphilin-3A