Priming-induced localization of G iα2 in high density membrane microdomains

Abstract

Subcellular fractionation of human neutrophils on linear sucrose density gradients was utilized to test the hypothesis that priming regulates the subcellular and sub-plasma membrane distribution of neutrophil G-protein subunits, G iα2 and G iα3, N-formyl peptide receptor, Lyn kinase and phospholipase C β2. G iα2, but not G iα3, moved from a lighter to a higher density plasma membrane fraction. Unoccupied N-formyl peptide receptors were found throughout the plasma membrane fractions and this distribution did not change with priming. In unprimed cells G iα2 and its effector, phospholipase C β2, were segregated in different membrane compartments; priming caused G iα2 to move to the compartment in which phospholipase C β2 resided. Thus, an important component of the mechanism of priming may involve regulation of the location of G-proteins and effector molecules in plasma membrane compartments where their abilities to couple may be enhanced.