Sodium-dependent transport of [3H](1D)chiro-inositol by Tetrahymena.
The transport characteristics of (1D)chiro-inositol by the ciliate Tetrahymena were examined in competition studies employing [3H](1D)chiro-inositol. (1D)chiro-Inositol transport was competed by unlabeled (1D)chiro-inositol, myo-inositol, scyllo-inositol, and D-glucose in a concentration-dependent manner. Conversely, (1D)chiro-inositol competed for [3H]myo- and [3H]scyllo-inositol transport. Lineweaver-Burke analysis of the competition data indicated a Km of 10.3 mM and a Bmax of 4.7 nmol/min/mg for (1D)chiro-inositol. Transport of (1D)chiro-inositol was inhibited by cytochalasin B, an inhibitor of facilitated glucose transporters, and phlorizin, an inhibitor of sodium-dependent transporters. Removal of sodium from the radiolabeling buffer also inhibited uptake. The presence of 0.64 mM calcium or magnesium ions exerted negligible effects on transport, although potassium was inhibitory. [3H](1D)chiro-Inositol was shown to be incorporated into Tetrahymena phosphoinositides.
Kersting
Michael C
MC
Department of Biochemistry and Molecular Biology, Mississippi State University, Mississippi State, Mississippi 39762, USA.
Ryals
Phillip E
PE
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D003571:Cytochalasin B / Q000494:pharmacology; D007294:Inositol / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D013768:Tetrahymena / Q000187:drug effects / Q000378:metabolism*; D014316:Tritium
D014316:Tritium; D003571:Cytochalasin B; D007294:Inositol; D012964:Sodium