Related Experiment Video
Updated: Oct 8, 2026

Quantitative Phosphoproteomics in Fatty Acid Stimulated Saccharomyces cerevisiae
Published on: October 12, 2009
Phosphatidylcholine biosynthesis via the CDP-choline pathway in Saccharomyces cerevisiae. Multiple mechanisms of
1Department of Molecular Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710.
Abstract:
Multiple mechanisms of regulation in the CDP-choline pathway for phosphatidylcholine (PC) synthesis were revealed by exploring the effects of choline and inositol on this pathway in Saccharomyces cerevisiae. At exogenous choline concentrations below 100 microM, phosphocholine cytidylyltransferase was rate-limiting; at higher choline concentrations the conversion of choline to phosphocholine by choline kinase became rate-limiting. Choline and inositol were found to regulate choline uptake; this established another regulatory mechanism by which PC synthesis is regulated in yeast. Inositol addition did not immediately affect labeled choline uptake or its incorporation into PC in actively dividing cells; however, preculturing the cells in the presence of choline decreased the rate of choline uptake, and this effect was amplified by the concomitant addition of inositol and choline. Additionally, a growth phase dependent effect of inositol supplementation was observed. Inositol addition to stationary phase cells resulted in an increase in choline uptake and subsequent PC production in these cells. This increase was shown to be due to an increase in the rate of choline transport into the cell. In the presence of inositol, choline transport is the main regulatory mechanism controlling flux through the CDP-choline pathway in S. cerevisiae. Inositol supplementation resulted in changes in the levels of enzyme activity detected in vitro. However, the effects observed in vivo correlated exclusively with changes in choline uptake. Choline transporter assays were consistent with these results. Since both the CPT1 and EPT1 gene products catalyze the cholinephosphotransferase reaction in vitro (Hjelmstad, R. H., and Bell, R. M. (1991) J. Biol. Chem. 266, 4357-4365), the effect of inositol on these two separate routes for PC biosynthesis was investigated. The data revealed that only cells harboring a functional CPT1 gene synthesized PC in vivo. These cells (ept1-delta 1::URA3) also displayed an identical mode of regulation in response to inositol as did cells containing an intact EPT1 gene (wild type) indicating there is no requirement for an alternate functional CDP-amino-alcohol pathway for inositol to regulate PC synthesis via the CDP-choline pathway.
More Related Videos
08:56Quantitative Analysis of the Cellular Lipidome of Saccharomyces Cerevisiae Using Liquid Chromatography Coupled with Tandem Mass Spectrometry
Published on: March 8, 2020
08:30Analysis of Neutral Lipid Synthesis in Saccharomyces cerevisiae by Metabolic Labeling and Thin Layer Chromatography
Published on: February 2, 2021
Related Concept Videos
Yeast Signaling
Regulation of Expression Occurs at Multiple Steps
Transcription results in the generation of precursor (pre-mRNA) that consists of both exons and introns, which needs further processing before being translated to a...
Phosphoinositides and PIPs
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
Synthesis of Phosphatidylcholine in the ER Membrane
The major components of all eukaryotic cell...
Biosynthesis of Polysaccharides
Bioreactor Controls-III