A new essential gene of Saccharomyces cerevisiae was found upstream of GCR1. Its cloning and sequencing predict a 280 amino acid protein (32,577 Da). The predicted protein is fairly hydrophobic, and a search of the database did not identify any homologous proteins. A LEU2 disruption at codon 104 was lethal, but disruption at codon 221 showed a temperature-sensitive conditional growth phenotype. Abnormalities were observed in some glycolytic enzyme levels.