Identification of Yeast Genes Involved in K+Homeostasis: Loss of Membrane Traffic Genes Affects K+Uptake

作者：Gillian L. Fell, Amanda M. Munson, Merriah A. Croston, Anne Rosenwald · 发表于：G3 Genes Genomes Genetics · 年份：2011 · DOI：10.1534/g3.111.000166 · 被引用次数：13 · 研究领域：Fungal and yeast genetics research、Plant nutrient uptake and metabolism、Cellular transport and secretion

Using the homozygous diploid Saccharomyces deletion collection, we searched for strains with defects in K(+) homeostasis. We identified 156 (of 4653 total) strains unable to grow in the presence of hygromycin B, a phenotype previously shown to be indicative of ion defects. The most abundant group was that with deletions of genes known to encode membrane traffic regulators. Nearly 80% of these membrane traffic defective strains showed defects in uptake of the K(+) homolog, (86)Rb(+). Since Trk1, a plasma membrane protein localized to lipid microdomains, is the major K(+) influx transporter, we examined the subcellular localization and Triton-X 100 insolubility of Trk1 in 29 of the traffic mutants. However, few of these showed defects in the steady state levels of Trk1, the localization of Trk1 to the plasma membrane, or the localization of Trk1 to lipid microdomains, and most defects were mild compared to wild-type. Three inositol kinase mutants were also identified, and in contrast, loss of these genes negatively affected Trk1 protein levels. In summary, this work reveals a nexus between K(+) homeostasis and membrane traffic, which does not involve traffic of the major influx transporter, Trk1.