Chemical modification of the neutral amino acid transport system L of Chinese hamster ovary cells with p-chloromercuribenzene sulfonate
Autor: | G S, Campbell, J H, Yu, D L, Oxender |
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Rok vydání: | 1992 |
Předmět: | |
Zdroj: | The Journal of biological chemistry. 267(18) |
ISSN: | 0021-9258 |
Popis: | Branched-chain and aromatic neutral amino acids enter mammalian cells predominantly through a Na(+)-independent transport agency called System L. The sulfhydryl specific reagent p-chloromercuribenzene sulfonate (pCMBS) has been shown to be a potent inactivator of System L transport activity in Chinese hamster ovary cells, however, inactivation by pCMBS can be prevented by the presence of System L-specific substrate amino acids during the inactivation reaction. In addition, the presence of amino acids that are not substrates for System L have no effect on pCMBS inactivation of System L. Inactivation of System L activity by pCMBS was sensitive to pH and reversible by incubation with dithiothreitol. These findings suggest that there is a sulfhydryl group in, or very near, the amino acid-binding site of the System L transporter of CHO cells. Substrate protection, however, could be explained by conformational changes in the transporter associated with substrate binding. The presence of a substrate protectable sulfhydryl group on the System L transporter would aid in the attempt to identify this transporter using the technique of differential labeling. |
Databáze: | OpenAIRE |
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