Bayer School of Natural and Environmental Sciences
Joseph R. McCormick
Phosphatidylinositol (PI) deacylation in Saccharomyces cerevisiae results in the formation and excretion of glycerophosphoinositol (GPI). This is a predominant route of PI turnover and is not unique to S. cerevisiae. Released GPI can be transported back into the cell through a membrane permease encoded by the GIT1 gene, Git1p. Maximum transport is achieved in low inositol/low phosphate conditions at pHs below 7, and the addition of a protonophore to the GPI transport assay abolishes transport activity. These findings suggest that Git1p is a proton symporter. An excess of unlabeled glycerol-3-phosphate (G3P) inhibits the transport of radiolabeled GPI into S. cerevisiae. Furthermore, radiolabeled G3P is transported into S. cerevisiae in a Git1p-dependent fashion. A GIT1 homolog from Schizosaccharomyces pombe (Sp-git1) was cloned. Overexpression of Sp-git1 did not result in increased transport of GPI into S. cerevisiae or S. pombe cells. However, it resulted in increased transport of inositol in S. pombe.
Nolder, C. (2003). Cloning and Characterization of a GIT1 Homolog Gene from Schizosaccharomyces Pombe (Master's thesis, Duquesne University). Retrieved from https://dsc.duq.edu/etd/986