Document Detail


Eight amino acid residues in transmembrane segments of yeast glucose transporter Hxt2 are required for high affinity transport.
MedLine Citation:
PMID:  16636054     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Hxt2 and Hxt1 are high affinity and low affinity facilitative glucose transporter paralogs of Saccharomyces cerevisiae, respectively, that differ at 75 amino acid positions in their 12 transmembrane segments (TMs). Comprehensive analysis of chimeras of these two proteins has previously revealed that TMs 1, 5, 7, and 8 of Hxt2 are required for high affinity glucose transport activity and that leucine 201 in TM5 is the most important in this regard of the 20 amino acid residues in these regions that differ between Hxt2 and Hxt1. To evaluate the importance of the remaining residues, we systematically shuffled the amino acids at these positions and screened the resulting proteins for high affinity and high capacity glucose transport activity. In addition to leucine 201 (TM5), four residues of Hxt2 (leucine 59 and leucine 61 in TM1, asparagine 331 in TM7, and phenylalanine 366 in TM8) were found to be important for such activity. Furthermore, phenylalanine 198 (TM5), alanine 363 (TM8), and either valine 316 (TM7) or alanine 368 (TM8) were found to be supportive of maximal activity. Construction of a homology model suggested that asparagine 331 interacts directly with the substrate and that the other identified residues may contribute to maintenance of protein conformation.
Authors:
Toshiko Kasahara; Masaji Ishiguro; Michihiro Kasahara
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-04-24
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  281     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  2006 Jul 
Date Detail:
Created Date:  2006-07-03     Completed Date:  2006-09-18     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  18532-8     Citation Subset:  IM    
Affiliation:
Laboratory of Biophysics, School of Medicine, Teikyo University, Hachioji, Tokyo 192-0395, Japan.
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MeSH Terms
Descriptor/Qualifier:
Amino Acid Motifs
Binding Sites / genetics
Biological Transport
Glucose / metabolism*
Glucose Transport Proteins, Facilitative
Membrane Proteins / chemistry*,  genetics,  metabolism
Models, Molecular
Molecular Sequence Data
Monosaccharide Transport Proteins / chemistry*,  genetics,  metabolism
Recombinant Fusion Proteins / chemistry,  metabolism
Saccharomyces cerevisiae / metabolism*
Saccharomyces cerevisiae Proteins / chemistry*,  genetics,  metabolism
Sequence Alignment
Structure-Activity Relationship
Chemical
Reg. No./Substance:
0/Glucose Transport Proteins, Facilitative; 0/HXT1 protein, S cerevisiae; 0/HXT2 protein, S cerevisiae; 0/Membrane Proteins; 0/Monosaccharide Transport Proteins; 0/Recombinant Fusion Proteins; 0/Saccharomyces cerevisiae Proteins; 50-99-7/Glucose

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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