Tritium thermal activation study of bacteriorhodopsin topography.

The action of thermally activated tritium on the purple membrane and delipidated bacteriorhodopsin fragments has been studied, tritium incorporation into specified amino acid residues being quantified by Edman degradation. The membrane environment was found to affect the accessibility of amino acid residues for tritium. Bacteriorhodopsin fragments 14-31, 45-63, 81-89, 171-179, and 210-225 were localized to the membrane interior while fragments 4-12, 32-44, 64-65, 73-80, and 156-170 should lie outside or close to membrane surface.

Complete amino acid sequence of gamma-subunit of the GTP-binding protein from cattle retina.

The complete amino acid sequence of the gamma-subunit of the GTP-binding protein from cattle retina has been established. The polypeptide chain of the gamma-subunit consists of 69 amino acid residues and contains the unusual sequence Cys35-Cys36. The Mr of the gamma-subunit is 8008.