These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Rat liver microsomal glucose-6-P translocase. Effect of physiological status on inhibition and labeling by stilbene disulfonic acid derivatives.
    Author: Zoccoli MA, Hoopes RR, Karnovsky ML.
    Journal: J Biol Chem; 1982 Oct 10; 257(19):11296-300. PubMed ID: 6288677.
    Abstract:
    Intact microsomes from groups of fed, fasted, glucocorticoid-treated (triamcinolone) and diabetic (alloxan) rats were reacted with 4,4'-diisothiocyanostilbene-2,2'-disulfonic (DIDS), a specific inhibitor of microsomal glucose-6-P translocase. The concentrations that inhibit by 50% were 41 +/- 2, 31 +/- 1, 39 +/- 4, and 18 +/- 1 microM (mean +/- S.E.; n = 3); (order as above). The maximal levels of inhibition of the translocase by DIDS were 66 +/- 2, 79 +/- 2, 63 +/- 1, and 88 +/- 1%, respectively. The differences in the values for the different groups of animals are statistically significant, except for comparisons between fed and triamcinolone-treated animals. Microsomes from the same groups of animals were treated with the tritiated reduced derivative of DIDS, [3H]H2DIDS, which labels a 54,000-dalton polypeptide, previously implicated as a component of the glucose-6-P translocase. The mean values (+/- S.E.) of [3H]H2DIDS bound to the polypeptide under saturating conditions were 100 +/- 6, 120 +/- 9, 62 +/- 7, and 101 +/- 15 pmol/mg of microsomal protein, respectively. The amount bound in microsomes from triamcinolone-treated rats is significantly lower from the values for the other three physiological states, which do not differ significantly from each other. The presence of glucose-6-P, but not mannose-6-P, during the [3H]H2DIDS reaction significantly stimulates the labeling of the 54,000-dalton polypeptide in microsomes from all the classes of animals above, except the diabetic animals. These results indicate that DIDS and [3H]H2DIDS are probes sensitive enough to discern differences in the translocase due to physiological regulation. On the basis of the labeling studies with [3H]H2DIDS, the increase in translocase activity observed in microsomes from fasted, triamcinolone-treated, and diabetic rats cannot be ascribed to increased numbers of translocase molecules, but rather to increased functional activity of the translocase protein.
    [Abstract] [Full Text] [Related] [New Search]