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: Biotin uptake by cold-shocked cells, spheroplasts, and repressed cells of Saccharomyces cerevisiae: lack of feedback control.
    Author: Cicmanec JF, Lichstein HC.
    Journal: J Bacteriol; 1974 Sep; 119(3):718-25. PubMed ID: 4604165.
    Abstract:
    Cold-osmotic-shocked cells and spheroplasts of Saccharomyces cerevisiae (ATCC 9896) display a biotin uptake system similar to that observed in intact cells. 2-Mercaptoethanol was found to inhibit biotin transport. Cells repressed for biotin uptake by growth in excess biotin (25 ng/ml) possess an energy-dependent transport system that has a K(m) for biotin of 6.6 x 10(-7) M and a V(max) equal to 39 pmol per mg (dry weight) per min. A similar K(m) (6.4 x 10(-7) M) but a considerably higher V(max) (530 pmol per mg (dry weight) per min) was determined for biotin uptake by cells grown in sufficient biotin (0.25 ng/ml). The V(max) rates of biotin uptake by both repressed and derepressed cells were increased approximately 35-fold in the presence of glucose. These yeast cells appear to regulate their biotin uptake by two mechanisms. An exit system provides for immediate adjustments, whereas turnover of the transport system and repression of new synthesis establishes a slower adaptation to changes in the environment. Feedback inhibition was ruled out as a mechanism of regulation of transport.
    [Abstract] [Full Text] [Related] [New Search]