The chromium(Ⅲ)-containing extract from Brewers yeast was first demonstrated to improve the phenomenon of impaired glucose tolerance,which was observed in rat fed with low-chromium diet and was defined as glucose tolerance factor (GTF).Saccharomyces sp.No.54 was chosen due to its highest GTF activity from yeast isolates.The differentiated 3T3L1 cell was used for GTF activity assay.The aims of this study are to purify a protein with GTF activity and to investigate the mechanism of its function.GTF crude extract from Saccharomyces sp.No.54 was passed through the DEAE cellulose column.Two protein fractions of DC1 and DC2 were collected.