Linked Life Data

2148692

Source:http://linkedlifedata.com/resource/pubmed/id/2148692

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
48
pubmed:dateCreated
1991-2-28
pubmed:abstractText
Transient exposure of human placental brush-border membrane vesicles to cholate reorients the ATP-driven H+ pump, enabling the pump to transport H+ into the vesicles upon addition of ATP to the external medium. H+ uptake can be measured in these vesicles by following the decrease in the absorbance of acridine orange, a delta pH indicator. We investigated the role of tyrosyl residues in the catalytic function of the H+ pump by studying the effects of tyrosyl group specific reagents on ATP-driven H+ uptake in cholate-pretreated membrane vesicles. The reagents tested were 7-chloro-4-nitro-2,1,3-benzoxadiazole (NBD-Cl), N-acetylimidazole, tetranitromethane, and p-nitrobenzenesulfonyl fluoride. Treatment of the membrane vesicles with these reagents resulted in the inhibition of the ATP-driven H+ uptake, and the inhibitory potency was in the following order: NBD-Cl greater than tetranitromethane greater than p-nitrobenzenesulfonyl fluoride greater than N-acetylimidazole. The inhibition of the H+ pump by NBD-Cl was reversible by 2-mercaptoethanol, and the inhibition by N-acetylimidazole was reversible by hydroxylamine. Since these reagents are not absolutely specific for tyrosyl groups and can also react with thiol groups, we studied the interaction of N-acetylimidazole with the H+ pump whose triol groups were masked by reaction with p-(chloromercuri)benzenesulfonate. The SH-masked pump was totally inactive, but the activity could be restored by dithiothreitol. On the contrary, the activity of the SH-masked H+ pump which was subsequently treated with N-acetylimidazole could not be restored by dithiothreitol, suggesting that thiol groups were not involved in the inhibition of the H+ pump by N-acetylimidazole.(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
4
pubmed:volume
29
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
10807-13
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1990
pubmed:articleTitle
The ATP-binding site of the human placental H+ pump contains essential tyrosyl residues.
pubmed:affiliation
Department of Cell and Molecular Biology, Medical College of Georgia, Augusta 30912-2100.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't