Do synapsin I and microtubule-associated proteins bind to a common site on polymerized tubulin?

Biochem Int. 1990 Dec;22(5):821-7.

Abstract

Synapsin I plays an important role in the regulation of neurotransmitter release, since it binds to synaptic vesicles and to the cytoskeleton, and it bundles F-actin and microtubules. We have previously shown by tryptic digestion of synapsin I that a 44 kDa fragment contains a binding site for polymerized tubulin. In the present experiments, we test whether synapsin I and microtubule-associated proteins (MAPs) have the same or a different binding site on tubulin molecules. Our results show that heat stable MAPs do not compete with synapsin I for binding to taxol tubulin. In addition, subtilisin digestion of tubulin, which suppresses MAPs binding, does not abolish synapsin I cosedimentation with taxol tubulin. Thus, our results strongly suggest that synapsin I (as reported for kinesin) does not bind to the 4 kDa subtilisin digested C-terminal part of the tubulin molecule.

MeSH terms

  • Animals
  • Binding Sites
  • Binding, Competitive
  • Cattle
  • Drug Stability
  • Hot Temperature
  • In Vitro Techniques
  • Microtubule-Associated Proteins / metabolism*
  • Nerve Tissue Proteins / metabolism*
  • Protein Binding
  • Synapsins
  • Tubulin / metabolism*

Substances

  • Microtubule-Associated Proteins
  • Nerve Tissue Proteins
  • Synapsins
  • Tubulin