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Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms
Uptake of system L amino acid substrates into isolated placental plasma membrane vesicles in the absence of opposing side amino acid (zero-trans uptake) is incompatible with the concept of obligatory exchange, where influx of amino acid is coupled to efflux. We therefore hypothesized that system L a...
Autores principales: | , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Federation of American Societies for Experimental Biology
2015
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4469330/ https://www.ncbi.nlm.nih.gov/pubmed/25761365 http://dx.doi.org/10.1096/fj.14-267773 |
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author | Widdows, Kate L. Panitchob, Nuttanont Crocker, Ian P. Please, Colin P. Hanson, Mark A. Sibley, Colin P. Johnstone, Edward D. Sengers, Bram G. Lewis, Rohan M. Glazier, Jocelyn D. |
author_facet | Widdows, Kate L. Panitchob, Nuttanont Crocker, Ian P. Please, Colin P. Hanson, Mark A. Sibley, Colin P. Johnstone, Edward D. Sengers, Bram G. Lewis, Rohan M. Glazier, Jocelyn D. |
author_sort | Widdows, Kate L. |
collection | PubMed |
description | Uptake of system L amino acid substrates into isolated placental plasma membrane vesicles in the absence of opposing side amino acid (zero-trans uptake) is incompatible with the concept of obligatory exchange, where influx of amino acid is coupled to efflux. We therefore hypothesized that system L amino acid exchange transporters are not fully obligatory and/or that amino acids are initially present inside the vesicles. To address this, we combined computational modeling with vesicle transport assays and transporter localization studies to investigate the mechanisms mediating [(14)C]l-serine (a system L substrate) transport into human placental microvillous plasma membrane (MVM) vesicles. The carrier model provided a quantitative framework to test the 2 hypotheses that l-serine transport occurs by either obligate exchange or nonobligate exchange coupled with facilitated transport (mixed transport model). The computational model could only account for experimental [(14)C]l-serine uptake data when the transporter was not exclusively in exchange mode, best described by the mixed transport model. MVM vesicle isolates contained endogenous amino acids allowing for potential contribution to zero-trans uptake. Both L-type amino acid transporter (LAT)1 and LAT2 subtypes of system L were distributed to MVM, with l-serine transport attributed to LAT2. These findings suggest that exchange transporters do not function exclusively as obligate exchangers.—Widdows, K. L., Panitchob, N., Crocker, I. P., Please, C. P., Hanson, M. A., Sibley, C. P., Johnstone, E. D., Sengers, B. G., Lewis, R. M., Glazier, J. D. Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms. |
format | Online Article Text |
id | pubmed-4469330 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2015 |
publisher | Federation of American Societies for Experimental Biology |
record_format | MEDLINE/PubMed |
spelling | pubmed-44693302015-06-23 Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms Widdows, Kate L. Panitchob, Nuttanont Crocker, Ian P. Please, Colin P. Hanson, Mark A. Sibley, Colin P. Johnstone, Edward D. Sengers, Bram G. Lewis, Rohan M. Glazier, Jocelyn D. FASEB J Research Communication Uptake of system L amino acid substrates into isolated placental plasma membrane vesicles in the absence of opposing side amino acid (zero-trans uptake) is incompatible with the concept of obligatory exchange, where influx of amino acid is coupled to efflux. We therefore hypothesized that system L amino acid exchange transporters are not fully obligatory and/or that amino acids are initially present inside the vesicles. To address this, we combined computational modeling with vesicle transport assays and transporter localization studies to investigate the mechanisms mediating [(14)C]l-serine (a system L substrate) transport into human placental microvillous plasma membrane (MVM) vesicles. The carrier model provided a quantitative framework to test the 2 hypotheses that l-serine transport occurs by either obligate exchange or nonobligate exchange coupled with facilitated transport (mixed transport model). The computational model could only account for experimental [(14)C]l-serine uptake data when the transporter was not exclusively in exchange mode, best described by the mixed transport model. MVM vesicle isolates contained endogenous amino acids allowing for potential contribution to zero-trans uptake. Both L-type amino acid transporter (LAT)1 and LAT2 subtypes of system L were distributed to MVM, with l-serine transport attributed to LAT2. These findings suggest that exchange transporters do not function exclusively as obligate exchangers.—Widdows, K. L., Panitchob, N., Crocker, I. P., Please, C. P., Hanson, M. A., Sibley, C. P., Johnstone, E. D., Sengers, B. G., Lewis, R. M., Glazier, J. D. Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms. Federation of American Societies for Experimental Biology 2015-06 2015-03-11 /pmc/articles/PMC4469330/ /pubmed/25761365 http://dx.doi.org/10.1096/fj.14-267773 Text en © The Author(s) http://creativecommons.org/licenses/by/4.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) (http://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Research Communication Widdows, Kate L. Panitchob, Nuttanont Crocker, Ian P. Please, Colin P. Hanson, Mark A. Sibley, Colin P. Johnstone, Edward D. Sengers, Bram G. Lewis, Rohan M. Glazier, Jocelyn D. Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms |
title | Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms |
title_full | Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms |
title_fullStr | Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms |
title_full_unstemmed | Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms |
title_short | Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms |
title_sort | integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms |
topic | Research Communication |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4469330/ https://www.ncbi.nlm.nih.gov/pubmed/25761365 http://dx.doi.org/10.1096/fj.14-267773 |
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