The patterns of membrane protein carboxyl-methylation by protein methylase II (S-adenosylmethionine: protein-carboxyl O-methyltransferase, EC 2.1.1.24) in intact human erythrocytes were shown to differ markedly whether the methyl donor, S-adenosyl-L-[methyl-3H]methionine, was supplied exogenously or formed intracellularly via exogenously added L-[methyl-3H]methionine. The differences include the following. (1) The methylation of cytoskeletal components (band 2.1 and 4.1) occurs only in the case of the L-[methyl-3H]methionine-labelled cells. (2) The methionine-mediated methylation was much less sensitive to S-adenosyl-L-homocysteine inhibition than the adenosylmethionine-mediated methylation (22% versus 95% inhibition at 10 microM). (3) The membrane protein methylation mediated by exogenous adenosylmethionine and methionine differed markedly in their alkali labilities; at pH 6.0, 30% of the adenosylmethionine-mediated protein methyl esters were hydrolysed after 30 min (37 degrees C) while the methionine-mediated esters were stable. At pH 7.4, the respective labilities were 60% and 30% for the 30 min incubation. To explain these results, a possible involvement of cytoskeletal structure associated with the intact erythrocyte is discussed.
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May 1984
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Research Article|
May 01 1984
Differential membrane protein carboxyl-methylation of intact human erythrocytes by exogenous methyl donors
Publisher: Portland Press Ltd
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 1984 London: The Biochemical Society
1984
Biochem J (1984) 219 (3): 743–749.
Citation
J Y Ro, P DiMaria, S Kim; Differential membrane protein carboxyl-methylation of intact human erythrocytes by exogenous methyl donors. Biochem J 1 May 1984; 219 (3): 743–749. doi: https://doi.org/10.1042/bj2190743
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