ULTRASTRUCTURAL-LOCALIZATION OF SNAP-25 WITHIN THE RAT SPINAL-CORD AND PERIPHERAL NERVOUS-SYSTEM

Synaptosomal associated protein of 25 kDa (SNAP-25) has been implicate d in the membrane fusion machinery of neurotransmitter release and axo nal growth. Using immunocytochemistry, we have analyzed the distributi on and ultrastructural localization of SNAP-25 in selected areas of th e central and peripheral nervous systems of adult rats. We show that t he protein is specifically expressed in the trans face of the Golgi ap paratus and in the axonal compartment. In axons and nerve endings, SNA P-25 is localized to discrete areas of the membranes of most organelle s such as the axoplasmic reticulum, the axolemma, the outer membrane o f mitochondria and synaptic vesicles. This wide distribution of SNAP-2 5 suggests that the protein is involved in the fusion of membranes in the whole axonal compartment of neurons. (C) 1995 Wiley-Liss, Inc.