Document Detail


Cys(294) is essential for the function of the human sodium-dependent multivitamin transporter.
MedLine Citation:
PMID:  22015582     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The sodium-dependent multivitamin transporter (SMVT) plays an important role in biotin uptake in the intestine and other cell types. While significant knowledge has been gained with regard to regulation and cell biology of the SMVT system, there is little known about its structure-function relationships. Here we examined the role of each of the ten conserved (among species) cysteine residues in the function of the human SMVT (hSMVT) using site-directed mutagenesis. Our results showed a significant impairment in biotin uptake only in cells transfected with hSMVT mutated at Cys(294), but not at the other conserved cysteine residues; the impairment in biotin uptake caused by mutating Cys(294) was not related to the polar status of substituting amino acid. The inhibition in hSMVT function upon mutating Cys(294) was mediated via a significant reduction in the V(max), but not the apparent K(m), of the biotin uptake process, suggesting a decrease in the number (and/or activity) of hSMVT but not affinity. Biotinylation assay confirmed this suggestion by showing a marked reduction in the level of expression of the mutated protein at the cell membrane, without affecting total cellular level of induced hSMVT. These results show an important role for Cys(294) in the function and cell biology of hSMVT.
Authors:
Abhisek Ghosal; Hamid M Said
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2011-10-12
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  1818     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2011-12-05     Completed Date:  2012-04-24     Revised Date:  2014-09-10    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  97-102     Citation Subset:  IM    
Copyright Information:
Copyright © 2011 Elsevier B.V. All rights reserved.
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MeSH Terms
Descriptor/Qualifier:
Biological Transport
Biotin / metabolism
Biotinylation
Cell Membrane / genetics,  metabolism*
Cysteine / genetics,  metabolism*
DNA Primers / chemistry,  genetics
Epithelial Cells / cytology,  metabolism*
Humans
Kinetics
Mutagenesis, Site-Directed
Mutation
Polymerase Chain Reaction
Retina / cytology,  metabolism*
Structure-Activity Relationship
Symporters / chemistry,  genetics,  metabolism*
Transfection
Grant Support
ID/Acronym/Agency:
DK56061/DK/NIDDK NIH HHS; DK58057/DK/NIDDK NIH HHS; R01 DK056061/DK/NIDDK NIH HHS; R01 DK056061-01/DK/NIDDK NIH HHS; R01 DK058057/DK/NIDDK NIH HHS; R01 DK058057-01/DK/NIDDK NIH HHS; R01 DK058057-06/DK/NIDDK NIH HHS
Chemical
Reg. No./Substance:
0/DNA Primers; 0/Symporters; 0/biotin transporter; 6SO6U10H04/Biotin; K848JZ4886/Cysteine
Comments/Corrections

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