The amino‐ and carboxyl‐terminal sequence of bovine rhodopsin

Abstract

Abstract The amino terminus of bovine rhodopsin is blocked and has the sequence x‐Met‐Asn(CHO)‐Gly‐Thr‐Glu‐Gly‐Pro‐Asn‐Phe‐Tyr‐Val‐Pro‐Phe‐Ser‐Asn(CHO)‐Lys‐Thr‐Gly‐Val‐Val‐Arg, where CHO represents sites of carbohydrate attachment. The carboxyl‐terminal sequence of rhodopsin is Val‐Ser‐Lys‐Thr‐Glu‐Thr‐Ser‐Gln‐Val‐Ala‐Pro‐Ala. Upon short‐term digestion of rod outer segment (ROS) membranes with thermolysin, opsin (∼ 35,000 daltons) is converted to a membrane‐bound fragment O′ (∼ 30,500 daltons) and 2 peptides containing 12 amino acids are released from the carboxyl terminus of rhodopsin into the supernatant. Upon long‐term digestion of ROS with thermolysin, opsin and O′ are replaced by the membrane‐bound fragments F 1 (∼25,000 daltons), and F 2 (∼9,500 daltons). When 32 P‐ROS are digested, F 2 carries the 32 P. Both O′ and F 1 contain the amino‐terminal glycopeptide.