Protein III is a synaptic vesicle-associated neuronal phosphoprotein which has been shown to be phosphorylated in intact nerve cell preparations by electrical stimulation in the presence of calcium, by depolarization in the presence of calcium, and by exogenous 8-bromo-cAMP. These and other data have led to the hypothesis that protein III pays some role in synaptic vesicle function. Protein III has recently been studied in the brain of normal and alcoholic humans. Protein III from the brains of normal humans and of alcoholics who died intoxicated (blood alcohol levels = more than 50mg/100 ml) appeared to migrate normally (i.e., protein IIIa was Mr=74,000 and protein IIIb was Mr=55,000) in SDS-polyacrylamide gels. However, in the brains of alcoholics who died sober (no detectable blood alcohol) variant forms of protein III (protein IIIa, Mr=76,000 and 78,000; protein IIIb, Mr=57,000 and 59,000) were seen in all brains examined (n=12). These data raise the possibiity that these variant forms of protein III may reflect sme underlying proces of significant import in alcoholism. The primary purpose of this proposal is to investigate protein III in terms of its role in normal neuronal function as well as its possible relationship to the neuropathology associated with alcoholism. The first step in this proposal involves purification and characterization of protein III in bovine brain and in the brains of normal and alcoholic humans. Molecular biological studies of the protein will then be conducted in order to determine the amino acid sequence of protein III in bovine brain and in the brains of normal and alcoholic humans. These studies will also be designed to anzlyse the synthesis and expression of protein III in bovine and human brain. Protein III will also be studied in human cerebrospinal fluid.
