NMR AND CIRCULAR-DICHROISM STUDIES OF SYNTHETIC PEPTIDES DERIVED FROMTHE 3RD INTRACELLULAR LOOP OF THE BETA-ADRENOCEPTOR

The C-terminal part of the third intracellular loop of the beta-adreno ceptor is capable of stimulating adenylate cyclase in the presence of phospholipid vesicles via the stimulatory guanine nucleotide binding p rotein (G(s)) [Palm et al. (1989) FEBS Lett. 254, 89-93]. We have inve stigated the structure of synthetic peptides corresponding to residues 284-295 of the turkey erythrocyte adrenoceptor in micelles, trifluoro ethanol and aqueous solution, by using 2D H-1 NMR and CD. In the prese nce of phospholipid micelles the peptides display a C-terminal alpha-h elical region, whereas the N-terminal part was found to be highly flex ible.