[Visual rhodopsin. III. Complete amino acid sequence and topography in a membrane]

Tryptic hydrolysis of apomembranes, BNPS-skatole cleavage of carboxymethylated rhodopsin and thermolytic digestion of native membranes were carried out to obtain the peptides necessary for the polypeptide chain reconstruction. Gel-filtration on Bio-Gel P-30 in 80% formic acid, ion-exchange and reversed-phase high performance liquid chromatography were used for the peptide isolation. A comparison of rhodopsin hydrophobicity profile with the accessibility of the polypeptide chain in native photoreceptor membranes for proteases allowed to distinguish seven alpha-helical segments and propose a model for arrangement of the protein molecule in the membrane.