Functional regions of the presynaptic cytomatrix protein bassoon: significance for synaptic targeting and cytomatrix anchoring

Mol Cell Neurosci. 2003 Jun;23(2):279-91. doi: 10.1016/s1044-7431(03)00015-0.

Abstract

Exocytosis of neurotransmitter from synaptic vesicles is restricted to specialized sites of the presynaptic plasma membrane called active zones. A complex cytomatrix of proteins exclusively assembled at active zones, the CAZ, is thought to form a molecular scaffold that organizes neurotransmitter release sites. Here, we have analyzed synaptic targeting and cytomatrix association of Bassoon, a major scaffolding protein of the CAZ. By combining immunocytochemistry and transfection of cultured hippocampal neurons, we show that the central portion of Bassoon is crucially involved in synaptic targeting and CAZ association. An N-terminal region harbors a distinct capacity for N-myristoylation-dependent targeting to synaptic vesicle clusters, but is not incorporated into the CAZ. Our data provide the first experimental evidence for the existence of distinct functional regions in Bassoon and suggest that a centrally located CAZ targeting function may be complemented by an N-terminal capacity for targeting to membrane-bounded synaptic organelles.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Differentiation / physiology
  • Cells, Cultured
  • Cytoskeleton / metabolism*
  • Cytoskeleton / ultrastructure
  • Fetus
  • Hippocampus / cytology
  • Hippocampus / embryology*
  • Hippocampus / metabolism*
  • Immunohistochemistry
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism*
  • Organelles / genetics
  • Organelles / metabolism
  • Presynaptic Terminals / metabolism*
  • Presynaptic Terminals / ultrastructure
  • Protein Structure, Tertiary / genetics
  • Protein Transport / genetics
  • Rats
  • Recombinant Fusion Proteins
  • Synaptic Membranes / metabolism*
  • Synaptic Membranes / ultrastructure
  • Synaptic Transmission / physiology
  • Synaptic Vesicles / metabolism*
  • Synaptic Vesicles / ultrastructure
  • Transfection

Substances

  • Bsn protein, rat
  • Nerve Tissue Proteins
  • Recombinant Fusion Proteins