Chapter 1 Molecular properties and cellular distribution of cholinergic synaptic proteins

Abstract

Publisher Summary This chapter discusses the molecular properties and cellular distribution of cholinergic synaptic proteins. Cholinergic synaptic vesicles share their major protein constituents with synaptic vesicles from non-specified transmitter type. The origin of the cholinergic synaptic vesicle membrane compartment and its recycling can be studied in the electromotor axon of the electric ray. Immunocytochemical evidence suggests that the synaptic vesicle integral membrane proteins synaptic vesicle protein 2 (SV2) and the vesicle associated small GTP-binding protein o-rab3 are associated with particulate yet differing organelles within the axon. As compared to the remainder of the axon the preterminal axon compartment appears to be very effectively cleared of vesicular membrane constituents. Calcium influx into synaptosomes is associated with the endogenous proteolysis of a pool of the synaptic vesicle proteins VAMP/synaptobrevin and synaptotagmin. Although the physiological function of this hydrolysis is not clear it may play a role in inactivating the synaptic vesicle within the presynaptic compartment. In addition to synaptic vesicles, cholinergic nerve terminal have a high content in proteinaceous particles that contain the major vault protein major vault protein (MVP) l00 as their major constituent, which may be physically linked to vesicles. The presence of the MVP containing protein particle in the nerve terminal implies new and yet unrecognized functional properties of this highly specialized compartment of the nerve cell.