Overexpression and Purification of the Glycerol Transport Facilitators, Fps1p and GlpF, in Saccharomyces Cerevisiae and Escherichia Coli

Abstract

Fpslp is an osmoregulated glycerol transport facilitator, located in the Saccharomyces cerevisiae plasma membrane, where it is mainly used for efflux of glycerol in the adaptation of yeast cells to lower external osmolarity (Luyten et al., 1995). Fpslp is an unusual member of the MIP (Major Intrinsic Protein)-family. The protein is much larger than most of the other proteins in the family, due to long hydrophilic extensions at both termini. The N-terminus (~250 aa) is involved in the regulation of the channel (Tamas et al., 1999), but the function of the C-terminus (~150 aa) is not yet known. Fpslp is also one of the few members that differs in the well-conserved NPA-motifs in the two putative channel forming loops B and E; serine instead of alanine in Loop B and leucine instead of proline in Loop E.