Ca2+-dependent formation of a dynamin-synaptophysin complex: potential role in synaptic vesicle endocytosis.
Synaptophysin is a synaptic vesicle (SV) protein of unknown function. Here we show that a repeated sequence in the cytoplasmic tail of synaptophysin mediates the formation of a protein complex containing the GTPase dynamin. The formation of this complex requires a high Ca(2+) concentration, suggesting that it occurs preferentially at the sites of SV exocytosis. Coimmunoprecipitation of a dynamin-synaptophysin complex from brain extracts is promoted by dissociation of vesicle-associated membrane protein 2 from synaptophysin. This finding suggests that dynamin only associates with synaptophysin in vivo after vesicle-associated membrane protein 2 (VAMP2) enters the SNARE complex. GTP binding releases dynamin from synaptophysin, possibly serving to regulate dynamin selfassembly during endocytosis. Our results suggest that synaptophysin plays a role in SV recycling by recruiting dynamin to the vesicle membrane.
Daly
Christopher
C
Howard Hughes Medical Institute and Department of Biochemistry, New York University Medical Center, New York, New York 10016, USA.
Ziff
Edward B
EB
D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D034281:Dynamins; D004705:Endocytosis; D020558:GTP Phosphohydrolases / Q000737:chemistry / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D050683:R-SNARE Proteins; D051381:Rats; D017207:Rats, Sprague-Dawley; D013572:Synaptic Vesicles / Q000378:metabolism*; D016708:Synaptophysin / Q000737:chemistry / Q000378:metabolism*
D008565:Membrane Proteins; D050683:R-SNARE Proteins; D016708:Synaptophysin; D006160:Guanosine Triphosphate; D020558:GTP Phosphohydrolases; D034281:Dynamins; D002118:Calcium