Enzymatic methylation of 23-29-kDa bovine retinal rod outer segment membrane proteins. Evidence for methyl ester formation at carboxyl-terminal cysteinyl residues.
J Biol Chem
; 264(22): 12879-84, 1989 Aug 05.
Article
em En
| MEDLINE
| ID: mdl-2753892
ABSTRACT
A group of 23-29-kDa polypeptides in the membranes of bovine rod outer segments are substrates for S-adenosylmethionine-dependent methylation reactions. The bulk of the methyl group incorporation is in base-labile ester-like linkages, and does not appear to be due to the widespread D-aspartyl/L-isoaspartyl methyltransferase (EC 2.1.1.77). To determine the site(s) of methylation, 3H-methylated proteins separated by polyacrylamide gel electrophoresis in sodium dodecyl sulfate were eluted and digested with papain, leucine aminopeptidase-M, and prolidase. After performic acid oxidation of the digest, a base-labile radioactive material was recovered that coeluted with a synthetic standard of cysteic acid methyl ester upon cation exchange and G-15 gel filtration chromatography, as well as in two thin-layer electrophoresis and two thin-layer chromatography systems. These results provide direct evidence for the methylation of the alpha-carboxyl group of a carboxyl-terminal cysteinyl residue, a modification that has been proposed for the 21-kDa Ha-ras product and other cellular proteins (Clarke, S., Vogel, J. P., Deschenes, R. J., and Stock, J. (1988) Proc. Natl. Acad. Sci. U. S. A. 85, 4643-4647).
Buscar no Google
Base de dados:
MEDLINE
Assunto principal:
Células Fotorreceptoras
/
Proteínas Metiltransferases
/
Proteína O-Metiltransferase
/
Segmento Externo da Célula Bastonete
/
Cisteína
/
Proteínas de Membrana
Idioma:
En
Ano de publicação:
1989
Tipo de documento:
Article