Effect of Ethanol Administration on the Phosphorylation of a 43KDa Synaptosomal Protein

Abstract

It is generally known that ethanol can freely enter the body organs and perturb cell membranes. The perturbation may, in turn, lead to changes in activity of neurotransmitters, ligand binding to receptors, ion fluxes, and enzyme activities (19). On chronic exposure to ethanol, the biologic system may develop adaptive mechanisms to overcome the perturbation. The physical and biochemical mechanisms by which ethanol alters membrane activities have not yet been clearly understood. However, phosphorylation is increasingly seen to be an ubiquitous biochemical mechanism for the modulation of membrane protein activity. Changes in phosphorylation of membrane proteins by ethanol may lead to changes in functional activity of the membrane (4,10,18). In a previous report (21), we have characterized the phosphorylation of a 43 kDa protein present in synaptosomes. An ecto-cellular protein kinase activity was suggested because the phosphorylation was very rapid (< 10 sec) and was dependent on Ca²⁺ and ATP (both available extracellularly) (21). The phosphorylation process was not dependent on cAMP or calmodulin. This 43kDa protein appears to be intimately related to Ca²⁺ movement across the synaptosomal membrane.