Isolation and biochemical characterization of a Ca2+-independent alpha-latrotoxin-binding protein

J Biol Chem. 1996 Sep 20;271(38):23239-45. doi: 10.1074/jbc.271.38.23239.


alpha-Latrotoxin, a black widow spider neurotoxin, can bind to high affinity receptors on the presynaptic plasma membrane and stimulate massive neurotransmitter release in the absence of Ca2+. Neurexins, previously isolated as alpha-latrotoxin receptors, require Ca2+ for their interaction with the toxin and, thus, may not participate in the Ca2+-independent alpha-latrotoxin activity. We now report the isolation of a novel protein that binds alpha-latrotoxin with high affinity in the presence of various divalent cations (Ca2+, Mg2+, Ba2+, and Sr2+) as well as in EDTA. This protein, termed here latrophilin, has been purified from detergent-solubilized bovine brain membranes by affinity chromatography on immobilized alpha-latrotoxin and concentrated on a wheat germ agglutinin affinity column. The single polypeptide chain of latrophilin is N-glycosylated and has an apparent molecular weight of 120,000. Sucrose gradient centrifugations demonstrated that latrophilin and alpha-latrotoxin form a stable equimolar complex. In the presence of the toxin, anti-alpha-latrotoxin antibodies precipitated iodinated latrophilin, whose binding to immobilized toxin was characterized by a dissociation constant of 0.5-0.7 nM. This presumably membrane-bound protein is localized to and differentially distributed among neuronal tissues, with about four times more latrophilin expressed in the cerebral cortex than in the cerebellum; subcellular fractionation showed that the protein is highly enriched in synaptosomal plasma membranes. Our data suggest that latrophilin may represent the Ca2+-independent receptor and/or molecular target for alpha-latrotoxin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Calcium / pharmacology*
  • Cattle
  • Membrane Glycoproteins / drug effects
  • Membrane Glycoproteins / isolation & purification
  • Membrane Glycoproteins / metabolism
  • Molecular Sequence Data
  • Nerve Tissue Proteins / drug effects
  • Nerve Tissue Proteins / isolation & purification
  • Nerve Tissue Proteins / metabolism*
  • Protein Binding
  • Rats
  • Receptors, Peptide / drug effects
  • Receptors, Peptide / isolation & purification
  • Receptors, Peptide / metabolism*
  • Sequence Analysis
  • Species Specificity
  • Spider Venoms / metabolism*
  • Synaptosomes / chemistry
  • Tissue Distribution


  • Membrane Glycoproteins
  • Nerve Tissue Proteins
  • Receptors, Peptide
  • Spider Venoms
  • alpha-latrotoxin receptor
  • alpha-latrotoxin
  • Calcium

Associated data

  • GENBANK/U78105