Ergosterol in plasma membrane of the yeast Saccharomyces cerevisiae

Kvasac Saccharomyces cerevisiae koristi se kao modelni organizam za proučavanje biosinteze sterola i njihove funkcije. Steroli su esencijalni lipidi koji tvore eukariotske membrane. U aerobnim uvjetima rasta, stanice kvasca sintetiziraju sterole, dok u anaerobnim uvjetima dolazi do unosa sterola iz okoline endocitozom. Višak slobodnih sterola esterificira se u endoplazmatskom retikulumu i pohranjuje u obliku lipidnih čestica. Biosinteza ergosterola je energetski skup proces koji uključuje put mevalonata. Prvi dio sinteze čine reakcije prevođenja acetil- CoA u farnezil pirofosfat, dok se drugi dio sinteze sastoji od nastajanja ergosterola iz farnezil fosfata. Visoka koncentracija etanola i hipoksijski uvjeti smanjuju sintezu ergosterola, dok povećanjem glukoze u podlozi koncentracija ergosterola raste.Saccharomyces cerevisiae is used as a model organisam for studying biosynthesis of sterols and their functions in yeast cell. Sterols are essential lipids that form eukaryotic membrane. In aerobic growth conditions, yeast cells synthesize sterols, while under anaerobic conditions sterols are imported by endocytosis. Free sterols are esterified in the endoplasmic reticulum and stored in the form of lipid particles. Ergosterol biosynthesis is energetically expensive process that involves mevalonate pathway. The first part of the synthesis consists of translation acetyl-CoA to farnesyl pyrophosphate, while the second part of the synthesis consists of the formation of ergosterol from farnesyl phosphate. High concentrations of ethanol and hypoxia reduce the synthesis of ergosterol, while higher concentrations of glucose in the medium helps the synthesis of ergosterol