The amino-terminal tryptic peptide of bovine rhodopsin. A glycopeptide containing two sites of oligosaccharide attachment.

A glycopeptide (T1) composed of 16 amino acids has been isolated from a tryptic digest of bovine rhodopsin. Its sequence is Met-Asn(CHO)-Gly-Thr-Glu-Gly-Pro-Asn-Phe-Tyr-Val-Pro-Phe-Ser-Asn(CHO)-Lys. Both rhodopsin and peptide T1 are blocked at their amino terminals. When a method specific for isolating amino-terminal tryptic peptides from proteins is applied to rhodopsin, peptide T1 is demonstrated to be the amino-terminal peptide of rhodopsin. Peptide T1 contains two sites at which carbohydrate is attached, whereas rhodopsin was previously thought to contain only a single such site.