Linked Life Data

11220362

Source:http://linkedlifedata.com/resource/pubmed/id/11220362

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2001-2-23
pubmed:abstractText
The dynamics of the glucose 6-phosphatase system were investigated in intact rat liver microsomes using a fast-sampling, rapid-filtration apparatus. Glucose and phosphate transport followed single exponential kinetics, appeared to be homogeneous, was unaffected by unlabeled substrate concentrations up to 100 mM, proved insensitive to various potential inhibitors, and demonstrated similarly low energies of activation. The extent of tracer accumulation from glucose 6-phosphate depended on which of the glucose or phosphate moieties was the labeled species in the parent molecule. The rates of tracer equilibration reflected those of glucose or phosphate transport but similar initial rates of uptake were observed for the glucose and phosphate products of hydrolysis. However, the latter accounted for only 12-13% of the steady-state rate of total glucose production. It is concluded that tracer uptake cannot represent substrate transport, that labeled glucose 6-phosphate at best represents a tiny fraction of the intramicrosomal glucose or phosphate pools, and that glucose 6-phosphate transport is not an obligatory prerequisite to its hydrolysis. The latter conclusion invalidates a major postulate of the substrate transport-catalytic unit concept but proves compatible with a conformational model whereby glucose 6-phosphate transport and hydrolysis are tightly coupled processes while glucose and phosphate share, along with water and a variety of other organic and inorganic solutes, a common porelike structure for their transport through the microsomal membrane.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0022-2631
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
179
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
113-26
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2001
pubmed:articleTitle
An integrated view of the kinetics of glucose and phosphate transport, and of glucose 6-phosphate transport and hydrolysis in intact rat liver microsomes.
pubmed:affiliation
Department of Nutrition, Faculté de Médecine, Université de Montréal, Canada.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't