Expression of GIRK (Kir3.1/Kir3.4) channels in mouse fibroblast cells withand without beta 1 integrins

G protein-activated K+ channel (GIRK) subunits possess a conserved extracel lular integrin-binding motif (RGD) and bind directly to beta 1 integrins, W e expressed GIRK1/GIRK4 channels labeled with green fluorescent protein in fibroblast cell lines expressing or lacking beta 1 integrins, Neither plasm a membrane localization nor agonist-evoked GIRK currents were affected by t he absence of beta 1 integrins or by incubation with externally applied RGD -containing peptide. Mutation of the aspartate (D) of RGD impaired currents , GIRK glycosylation, and membrane localization, but the interaction with b eta 1 integrins remained intact. Thus, beta 1 integrins are not essential f or functional GIRK expression; and the GIRK-integrin interactions involve s tructural elements other than the RGD motif. (C) 2000 Federation of Europea n Biochemical Societies.