Glycerophosphocholine is formed via the deacylation of the phospholipid phosphatidylcholine. The protein encoded by Saccharomyces cerevisiae open reading frame YPL110c effects glycerophosphocholine metabolism in vivo, most likely by acting as a glycerophosphocholine phosphodiesterase. Deletion of YPL110c causes an accumulation of glycerophosphocholine in cells prelabeled with 14Ccholine. Correspondingly, overexpression of YPL110c results in reduced intracellular glycerophosphocholine in cells prelabeled with 14Ccholine. Glycerophospho3Hcholine supplied in the growth medium accumulates to a much greater extent in the intracellular fraction of a YPL110Δ strain than in a wild type strain. Furthermore, glycerophospho3Hcholine accumulation requires the transporter encoded by GIT1, a known glycerophosphoinositol transporter. Growth on glycerophosphocholine as the sole phosphate source requires YPL110c and the Git1p permease. In contrast to glycerophosphocholine, glycerophosphoinositol metabolism is unaffected by deletion of YPL110c. The open reading frame YPL110c has been termed GDE1.