Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9886539 | Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids | 2005 | 8 Pages |
Abstract
Lanosterol C-14 demethylase Erg11p of the yeast Saccharomyces cerevisiae catalyzes the enzymatic step following formation of lanosterol by the lanosterol synthase Erg7p in lipid particles (LP). Localization experiments employing microscopic inspection and cell fractionation revealed that Erg11p in contrast to Erg7p is associated with the endoplasmic reticulum (ER). An erg11Î mutation in erg3Î background, which is required to circumvent lethality of the erg11 defect, did not only change the sterol pattern but also the sterol distribution within the cell. Whereas in wild type the plasma membrane was highly enriched in ergosterol and LP harbored large amounts of sterol precursors in the form of steryl esters, sterol intermediates were more or less evenly distributed among organelles of erg11Î erg3Î. This distribution is not result of the erg3Î background, because in the erg3Î strain the major intermediate formed, ergosta-7,22-dienol, is also highly enriched in the plasma membrane similar to ergosterol in wild type. These results indicate that (i) exit of lanosterol from LP occurs independently of functional Erg11p, (ii) random supply of sterol intermediates to all organelles of erg11Î erg3Î appears to compensate for the lack of ergosterol in this mutant, and (iii) preferential sorting of ergosterol in wild type, but also of ergosta-7,22-dienol in erg3Î, supplies sterol to the plasma membrane.
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Authors
René G. Ott, Karin Athenstaedt, Claudia Hrastnik, Erich Leitner, Helmut Bergler, Günther Daum,