Synapsin I is a microtubule-bundling protein.

Journal Article

Synapsin I, a synaptic vesicle protein, is thought to be involved in the regulation of neurotransmission through its phosphorylation by the cyclic AMP-dependent and Ca2+/calmodulin-dependent protein kinases which become activated upon depolarization of nerve endings. However, despite its recent characterization as a spectrin-binding protein immunologically related to erythrocyte protein 4.1, other interactions of synapsin I with structural proteins remain unknown. We report here that synapsin I can co-cycle with microtubules through three cycles of warm polymerization and cold depolymerization. Synapsin I binds saturably to microtubules stabilized by taxol, with an estimated dissociation constant (Kd) of 4.5 microM and a stoichiometry of 1.2 mol of synapsin binding sites per mol tubulin dimer. Synapsin I also increases the turbidity of tubulin solutions at 37 degrees C, but without causing detectable alterations in the critical concentration required for polymerization. Mixtures of synapsin I and tubulin observed by negative stain electron microscopy contain bundles of microtubules, accounting for the effect of synapsin I on tubulin turbidity. Synapsin I is thus a candidate to mediate or regulate the interaction of synaptic vesicles with microtubules.

Full Text

Duke Authors

Cited Authors

  • Baines, AJ; Bennett, V

Published Date

  • January 9, 1986

Published In

Volume / Issue

  • 319 / 6049

Start / End Page

  • 145 - 147

PubMed ID

  • 2417124

International Standard Serial Number (ISSN)

  • 0028-0836

Digital Object Identifier (DOI)

  • 10.1038/319145a0

Language

  • eng

Conference Location

  • England