MUTATIONAL ANALYSIS OF THE MOUSE 5-HT7 RECEPTOR - IMPORTANCE OF THE 3RD INTRACELLULAR LOOP FOR RECEPTOR-G-PROTEIN INTERACTION

The mouse serotonin (5-HT) receptor subtype, 5-HT7, belongs to the fam ily of seven transmembrane G-protein-coupled receptors, To identify th e structural basis for the coupling of 5-HT7 receptor to G alpha(S) we constructed a number of receptor mutants in which amino acid residues were either substituted or deleted from the second and third intracel lular loops, Wild-type and mutant 5-HT7 receptors were expressed in in sect cells using the baculovirus vectors, Two mutant receptor species, 5-HT7(E325G) and 5-HT7(K327S), demonstrated markedly impaired abiliti es to stimulate adenylyl cyclase. The results suggest the importance o f the C-terminal region of the third intracellular loop in receptor-G- protein interaction and that specific charged residues, E325 and K327, may play a critical role in this interaction. (C) 1997 Federation of European Biochemical Societies.