IDENTIFICATION AND ANALYSIS OF A STATIC CULTURE-SPECIFIC CELL-WALL PROTEIN, TIR1P SRP1P IN SACCHAROMYCES-CEREVISIAE/

A 100-kDa protein was found to be a major cell wall protein in Sacchar omyces cerevisiae cells cultured without shaking, but was not present in cells cultured with shaking. The amino acid sequence of this protei n was identical to the sequence of Tir1p/Srp1p. TIR1/SRP1 has previous ly been identified as a gene induced by glucose, cold shock or anaerob iosis and was believed to be a cell membrane protein but not a cell wa ll protein. However, we found that beta-1,3-glucanase solubilized Tir1 p/Srp1p from the cell wall and the purified Tir1p/Srp1p reacted with a ntiserum to beta-1,6-glucan and contained glucose. These results sugge st that Tir1p/Srp1p is a major structural cell wall protein in the sta tic-cultured yeast cells and is bound to the cell wall through beta-1, 6-glucan. TIR1/SRP1 mRNA was transcribed only in the static culture an d its transcription was regulated by the ROX1 repressor.