Priming-induced localization of Giα3 in high density membrane microdomains

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(ialpha2) and G(ialpha3), N-formyl peptide receptor, Lyn kinase and phospholipase C-beta2. G(ialpha2), but not G(ialpha3), 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 imprinted cells G(ialpha2) and its effector, phospholipase C-beta2, were segregated in different membrane compartments; priming caused G(ialpha2) to move to the compartment in which phospholipase C-beta2 resided. Thus, an important component of the mechanism of priming may involve regulation of the location of G-protems and effector molecules in plasma membrane compartments where their abilities to couple may be enhanced. (C) 2003 Elsevier Science (USA). All rights reserved.