Publications [#112860] of G Vann V. Bennett

Papers Published

1. AJ Baines, V Bennett, Synapsin I is a microtubule-bundling protein., Nature, ENGLAND, vol. 319 no. 6049 , pp. 145-7, ISSN 0028-0836
   (last updated on 2003/02/18)

   Abstract:
   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.

   Keywords:
   Alkaloids • Animals • Axonal Transport • Brain Chemistry • Cattle • Microscopy, Electron • Microtubule-Associated Proteins • Nerve Tissue Proteins • Paclitaxel • Protein Binding • Synapsins • Synaptic Vesicles* • Tubulin • metabolism • metabolism* • pharmacology