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J Bacteriol

Title:		Mutations within the first LSGGQ motif of Ste6p cause defects in a-factor transport and mating in Saccharomyces cerevisiae
Author(s):		Browne BL; McClendon V; Bedwell DM;
Address:		"Department of Microbiology,University of Alabama, Birmingham, Alabama 35294, USA"
Journal Title:		J Bacteriol
Year:		1996
Volume:		178
Issue:		6
Page Number:		1712 - 1719
DOI:		10.1128/jb.178.6.1712-1719.1996
ISSN/ISBN:		0021-9193 (Print) 1098-5530 (Electronic) 0021-9193 (Linking)
Abstract:		"Mating between the two haploid cell types (a and alpha) of the yeast Saccharomyces cerevisiae depends upon the efficient secretion and delivery of the a- and alpha-factor pheromones to their respective target cells. However, a quantitative correlation between the level of transported a-factor and mating efficiency has never been determined. a-Factor is transported by Ste6p, a member of the ATP-binding cassette (ABC) family of transporter proteins. In this study, several missense mutations were introduced in or near the conserved LSGGQ motif within the first nucleotide-binding domain of Ste6p. Quantitation of extracellular a-factor levels indicated that these mutations caused a broad range of a-factor transport defects, and those directly within the LSGGQ motif caused the most severe defects. Overall, we observed a strong correlation between the level of transported a-factor and the mating efficiency of these strains, consistent with the role of Ste6p as the a-factor transporter. The LSGGQ mutations did not cause either a significant alteration in the steady-state level of Ste6p or a detectable change in its subcellular localization. Thus, it appears that these mutations interfere with the ability of Ste6p to transport a-factor out of the MATa cell. The possible involvement of the LSGGQ motif in transporter function is consistent with the strong conservation of this sequence motif throughout the ABC transporter superfamily"
Keywords:		ATP-Binding Cassette Transporters/*genetics Amino Acid Sequence Biological Transport Cell Compartmentation Fungal Proteins/*genetics/*metabolism *Glycoproteins Lipoproteins/*metabolism Molecular Sequence Data Mutagenesis Phenotype Pheromones/*metabolism R;
Notes:		"MedlineBrowne, B L McClendon, V Bedwell, D M eng DK50832/DK/NIDDK NIH HHS/ Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S. 1996/03/01 J Bacteriol. 1996 Mar; 178(6):1712-9. doi: 10.1128/jb.178.6.1712-1719.1996"