Interaction of free and synaptic vesicle-bound synapsin I with F-actin.
Synapsin I is a neuron-specific phosphoprotein that binds to small synaptic vesicles and F-actin in a phosphorylation-dependent fashion. We have found that dephosphorylated synapsin I induces a dose-dependent increase in the number of actin filaments, which at high ionic strength is abolished by synapsin I phosphorylation. The increase in filament number appears to be due to a nucleating effect of synapsin I and not to a barbed-end capping/severing activity. Synaptic vesicle-bound synapsin I was as effective as free synapsin I in increasing the number of filaments. These data support the view that synapsin I is involved in the regulation of the dynamics of the actin-based network during the exo-endocytotic cycle.
Benfenati
F
F
Institute of Human Physiology, University of Modena, Italy.
Valtorta
F
F
Chieregatti
E
E
Greengard
P
P
D008841:Actin Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D000199:Actins / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D003571:Cytochalasin B / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D008854:Microscopy, Electron; D010766:Phosphorylation; D011108:Polymers; D016548:Prosencephalon / Q000648:ultrastructure; D011485:Protein Binding; D051381:Rats; D016704:Synapsins / Q000032:analysis* / Q000378:metabolism* / Q000494:pharmacology; D013572:Synaptic Vesicles / Q000737:chemistry* / Q000648:ultrastructure; D014316:Tritium
D000199:Actins; D011108:Polymers; D016704:Synapsins; D014316:Tritium; D003571:Cytochalasin B