NMR and circular dichroism studies of synthetic peptides derived from the third intracellular loop of the β‐adrenoceptor

The C-terminal part of the third intracellular loop of the beta-adrenoceptor is capable of stimulating adenylate cyclase in the presence of phospholipid vesicles via the stimulatory guanine nucleotide binding protein (Gs) [Palm et al. (1989) FEBS Lett. 254, 89-93]. We have investigated the structure of synthetic peptides corresponding to residues 284-295 of the turkey erythrocyte adrenoceptor in micelles, trifluoroethanol and aqueous solution, by using 2D 1H NMR and CD. In the presence of phospholipid micelles the peptides display a C-terminal alpha-helical region, whereas the N-terminal part was found to be highly flexible.