Tetanus toxin-sensitive VAMP-related proteins are present in murine macrophages.

The light chain of tetanus neurotoxin (TeTx) is a zinc endopeptidase specific for VAMP/synaptobrevin (VAMP), a 120-amino-acid integral protein previously described in the small synaptic vesicles of neuronal cells. TeTx has been shown to be active also on nonneuronal cells. By SDS-PAGE and quantitative immunoblotting on proteins derived from murine macrophages (Mphi) exposed to TeTx, we have shown that: (1) VAMP-related proteins are also present in Mphi and (2) such proteins are sensitive to TeTx proteolytic cleavage. The demonstration that TeTx acts on VAMP-related proteins also in Mphi offers a new and useful tool for molecular studies on Mphi exocytosis.