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 (Mφ) exposed to TeTx, we have shown that: (1) VAMP-related proteins are also present in Mφ and (2) such proteins are sensitive to TeTx proteolytic cleavage. The demonstration that TeTx acts on VAMP-related proteins also in Mφ offers a new and useful tool for molecular studies on Mφ exocytosis.