Linked Life Data

17932225

Source:http://linkedlifedata.com/resource/pubmed/id/17932225

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
2007-12-10
pubmed:abstractText
This study presents the characterization of myo-inositol (MI) uptake in rat intestine as evaluated by use of purified membrane preparations. Three secondary active MI cotransporters have been identified; two are Na(+) coupled (SMIT1 and SMIT2) and one is H(+) coupled (HMIT). Through inhibition studies using selective substrates such as d-chiro-inositol (DCI, specific for SMIT2) and l-fucose (specific for SMIT1), we show that SMIT2 is exclusively responsible for apical MI transport in rat intestine; rabbit intestine appears to lack apical transport of MI. Other sugar transport systems known to be present in apical membranes, such as SGLT1 or GLUT5, lacked any significant contribution to MI uptake. Functional analysis of rat SMIT2 activity, via electrophysiological studies in Xenopus oocytes, demonstrated similarities to the activities of SMIT2 from other species (rabbit and human) displaying high affinities for MI (0.150 +/- 0.040 mM), DCI (0.31 +/- 0.06 mM), and phlorizin (Pz; 0.016 +/- 0.007 mM); low affinity for glucose (36 +/- 7 mM); and no affinity for l-fucose. Although these functional characteristics essentially confirmed those found in rat intestinal apical membranes, a unique discrepancy was seen between the two systems studied in that the affinity constant for glucose was approximately 40-fold lower in vesicles (K(i) = 0.94 +/- 0.35 mM) than in oocytes. Finally, the transport system responsible for the basolateral efflux transporter of glucose in intestine, GLUT2, did not mediate any significant radiolabeled MI uptake in oocytes, indicating that this transport system does not participate in the basolateral exit of MI from small intestine.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0193-1857
pubmed:author
pubmed:issnType
Print
pubmed:volume
293
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
G1300-7
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
SMIT2 mediates all myo-inositol uptake in apical membranes of rat small intestine.
pubmed:affiliation
Groupe d'étude des protéines membranaires (GEPROM), Département de Physiologie, Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, Québec, Canada, H3C 3J7.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't