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Kinetics and Stoichiometry of a Proton/myo-Inositol Cotransporter
Voltage clamp recording was used to measure steady-state and presteady-state currents mediated by a myo -inositol transporter cloned from Leishmania donovani and expressed in Xenopus oocytes. Application of myo -inositol resulted in inward currents, which did not require external sodium and which we...
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| Published in: | The Journal of biological chemistry 1996-06, Vol.271 (25), p.14937-14943 |
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| Format: | Article |
| Language: | English |
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| container_end_page | 14943 |
| container_issue | 25 |
| container_start_page | 14937 |
| container_title | The Journal of biological chemistry |
| container_volume | 271 |
| creator | Klamo, E M Drew, M E Landfear, S M Kavanaugh, M P |
| description | Voltage clamp recording was used to measure steady-state and presteady-state currents mediated by a myo -inositol transporter cloned from Leishmania donovani and expressed in Xenopus oocytes. Application of myo -inositol resulted in inward currents, which did not require external sodium and which were increased by increasing the extracellular
proton concentration and by membrane hyperpolarization. Alkalinization of the extracellular space occurred concomitantly with
myo -inositol influx. Correlation of membrane currents with radiolabeled myo -inositol flux revealed that one positive charge is translocated with each molecule of myo -inositol, consistent with cotransport of one proton. The transport concentration dependence on both species suggested ordered
binding of a proton followed by a molecule of myo -inositol. In the absence of myo -inositol, a voltage-dependent capacitance was observed that correlated with the transporter expression level. This charge
movement obeyed a Boltzmann function, which was used to estimate a turnover of 0.70 ± 0.06 s â1 at â60 mV. The pH and voltage dependence of the charge movements were simulated with a model involving alternating access
of internal and external protons to sites within an occluded pore. |
| doi_str_mv | 10.1074/jbc.271.25.14937 |
| format | article |
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proton concentration and by membrane hyperpolarization. Alkalinization of the extracellular space occurred concomitantly with
myo -inositol influx. Correlation of membrane currents with radiolabeled myo -inositol flux revealed that one positive charge is translocated with each molecule of myo -inositol, consistent with cotransport of one proton. The transport concentration dependence on both species suggested ordered
binding of a proton followed by a molecule of myo -inositol. In the absence of myo -inositol, a voltage-dependent capacitance was observed that correlated with the transporter expression level. This charge
movement obeyed a Boltzmann function, which was used to estimate a turnover of 0.70 ± 0.06 s â1 at â60 mV. The pH and voltage dependence of the charge movements were simulated with a model involving alternating access
of internal and external protons to sites within an occluded pore.</description><identifier>ISSN: 0021-9258</identifier><identifier>EISSN: 1083-351X</identifier><identifier>DOI: 10.1074/jbc.271.25.14937</identifier><identifier>PMID: 8663013</identifier><language>eng</language><publisher>United States: American Society for Biochemistry and Molecular Biology</publisher><subject>Animals ; Biological Transport ; Carrier Proteins - biosynthesis ; Carrier Proteins - metabolism ; Female ; Hydrogen-Ion Concentration ; Inositol - metabolism ; Inositol - pharmacology ; Kinetics ; Leishmania donovani ; Leishmania donovani - metabolism ; Membrane Potentials - drug effects ; Models, Biological ; Oocytes - drug effects ; Oocytes - physiology ; Patch-Clamp Techniques ; Temperature ; Xenopus laevis</subject><ispartof>The Journal of biological chemistry, 1996-06, Vol.271 (25), p.14937-14943</ispartof><lds50>peer_reviewed</lds50><oa>free_for_read</oa><woscitedreferencessubscribed>false</woscitedreferencessubscribed></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><link.rule.ids>314,776,780,27901,27902</link.rule.ids><backlink>$$Uhttps://www.ncbi.nlm.nih.gov/pubmed/8663013$$D View this record in MEDLINE/PubMed$$Hfree_for_read</backlink></links><search><creatorcontrib>Klamo, E M</creatorcontrib><creatorcontrib>Drew, M E</creatorcontrib><creatorcontrib>Landfear, S M</creatorcontrib><creatorcontrib>Kavanaugh, M P</creatorcontrib><title>Kinetics and Stoichiometry of a Proton/myo-Inositol Cotransporter</title><title>The Journal of biological chemistry</title><addtitle>J Biol Chem</addtitle><description>Voltage clamp recording was used to measure steady-state and presteady-state currents mediated by a myo -inositol transporter cloned from Leishmania donovani and expressed in Xenopus oocytes. Application of myo -inositol resulted in inward currents, which did not require external sodium and which were increased by increasing the extracellular
proton concentration and by membrane hyperpolarization. Alkalinization of the extracellular space occurred concomitantly with
myo -inositol influx. Correlation of membrane currents with radiolabeled myo -inositol flux revealed that one positive charge is translocated with each molecule of myo -inositol, consistent with cotransport of one proton. The transport concentration dependence on both species suggested ordered
binding of a proton followed by a molecule of myo -inositol. In the absence of myo -inositol, a voltage-dependent capacitance was observed that correlated with the transporter expression level. This charge
movement obeyed a Boltzmann function, which was used to estimate a turnover of 0.70 ± 0.06 s â1 at â60 mV. The pH and voltage dependence of the charge movements were simulated with a model involving alternating access
of internal and external protons to sites within an occluded pore.</description><subject>Animals</subject><subject>Biological Transport</subject><subject>Carrier Proteins - biosynthesis</subject><subject>Carrier Proteins - metabolism</subject><subject>Female</subject><subject>Hydrogen-Ion Concentration</subject><subject>Inositol - metabolism</subject><subject>Inositol - pharmacology</subject><subject>Kinetics</subject><subject>Leishmania donovani</subject><subject>Leishmania donovani - metabolism</subject><subject>Membrane Potentials - drug effects</subject><subject>Models, Biological</subject><subject>Oocytes - drug effects</subject><subject>Oocytes - physiology</subject><subject>Patch-Clamp Techniques</subject><subject>Temperature</subject><subject>Xenopus laevis</subject><issn>0021-9258</issn><issn>1083-351X</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>1996</creationdate><recordtype>article</recordtype><recordid>eNqFkEtLw0AAhBdRaq3evQg5iLeku9lnjqX4KBYUVPAW9hWzJcnW3S3Sf2-wvTuXOczHHD4ArhEsEORkvlG6KDkqSlogUmF-AqYICpxjij5PwRTCEuVVScU5uIhxA8eQCk3ARDCGIcJTsHh2g01Ox0wOJntL3unW-d6msM98k8nsNfjkh3m_9_lq8NEl32VLn4Ic4taHZMMlOGtkF-3VsWfg4-H-ffmUr18eV8vFOm9RJVJOuEFcS8KMtQRSY4RBWEHGNGeEaM20VBAxLaTEhlDSUKVVI1RVacorUuIZuDv8boP_3tmY6t5FbbtODtbvYs0FwhiW_4OICgoRpyN4cwR3qrem3gbXy7Cvj3LG_fawt-6r_XHB1sp53dq-HpXXJa3_lONfqmdysA</recordid><startdate>19960621</startdate><enddate>19960621</enddate><creator>Klamo, E M</creator><creator>Drew, M E</creator><creator>Landfear, S M</creator><creator>Kavanaugh, M P</creator><general>American Society for Biochemistry and Molecular Biology</general><scope>CGR</scope><scope>CUY</scope><scope>CVF</scope><scope>ECM</scope><scope>EIF</scope><scope>NPM</scope><scope>M7N</scope><scope>7X8</scope></search><sort><creationdate>19960621</creationdate><title>Kinetics and Stoichiometry of a Proton/myo-Inositol Cotransporter</title><author>Klamo, E M ; Drew, M E ; Landfear, S M ; Kavanaugh, M P</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-h198t-47d17ca46dee405dd8d13b066c7644cc6cab016c8aa3d454f5bcbf8b99c579423</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>1996</creationdate><topic>Animals</topic><topic>Biological Transport</topic><topic>Carrier Proteins - biosynthesis</topic><topic>Carrier Proteins - metabolism</topic><topic>Female</topic><topic>Hydrogen-Ion Concentration</topic><topic>Inositol - metabolism</topic><topic>Inositol - pharmacology</topic><topic>Kinetics</topic><topic>Leishmania donovani</topic><topic>Leishmania donovani - metabolism</topic><topic>Membrane Potentials - drug effects</topic><topic>Models, Biological</topic><topic>Oocytes - drug effects</topic><topic>Oocytes - physiology</topic><topic>Patch-Clamp Techniques</topic><topic>Temperature</topic><topic>Xenopus laevis</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Klamo, E M</creatorcontrib><creatorcontrib>Drew, M E</creatorcontrib><creatorcontrib>Landfear, S M</creatorcontrib><creatorcontrib>Kavanaugh, M P</creatorcontrib><collection>Medline</collection><collection>MEDLINE</collection><collection>MEDLINE (Ovid)</collection><collection>MEDLINE</collection><collection>MEDLINE</collection><collection>PubMed</collection><collection>Algology Mycology and Protozoology Abstracts (Microbiology C)</collection><collection>MEDLINE - Academic</collection><jtitle>The Journal of biological chemistry</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Klamo, E M</au><au>Drew, M E</au><au>Landfear, S M</au><au>Kavanaugh, M P</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>Kinetics and Stoichiometry of a Proton/myo-Inositol Cotransporter</atitle><jtitle>The Journal of biological chemistry</jtitle><addtitle>J Biol Chem</addtitle><date>1996-06-21</date><risdate>1996</risdate><volume>271</volume><issue>25</issue><spage>14937</spage><epage>14943</epage><pages>14937-14943</pages><issn>0021-9258</issn><eissn>1083-351X</eissn><abstract>Voltage clamp recording was used to measure steady-state and presteady-state currents mediated by a myo -inositol transporter cloned from Leishmania donovani and expressed in Xenopus oocytes. Application of myo -inositol resulted in inward currents, which did not require external sodium and which were increased by increasing the extracellular
proton concentration and by membrane hyperpolarization. Alkalinization of the extracellular space occurred concomitantly with
myo -inositol influx. Correlation of membrane currents with radiolabeled myo -inositol flux revealed that one positive charge is translocated with each molecule of myo -inositol, consistent with cotransport of one proton. The transport concentration dependence on both species suggested ordered
binding of a proton followed by a molecule of myo -inositol. In the absence of myo -inositol, a voltage-dependent capacitance was observed that correlated with the transporter expression level. This charge
movement obeyed a Boltzmann function, which was used to estimate a turnover of 0.70 ± 0.06 s â1 at â60 mV. The pH and voltage dependence of the charge movements were simulated with a model involving alternating access
of internal and external protons to sites within an occluded pore.</abstract><cop>United States</cop><pub>American Society for Biochemistry and Molecular Biology</pub><pmid>8663013</pmid><doi>10.1074/jbc.271.25.14937</doi><tpages>7</tpages><oa>free_for_read</oa></addata></record> |
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| identifier | ISSN: 0021-9258 |
| ispartof | The Journal of biological chemistry, 1996-06, Vol.271 (25), p.14937-14943 |
| issn | 0021-9258 1083-351X |
| language | eng |
| recordid | cdi_proquest_miscellaneous_78133022 |
| source | ScienceDirect |
| subjects | Animals Biological Transport Carrier Proteins - biosynthesis Carrier Proteins - metabolism Female Hydrogen-Ion Concentration Inositol - metabolism Inositol - pharmacology Kinetics Leishmania donovani Leishmania donovani - metabolism Membrane Potentials - drug effects Models, Biological Oocytes - drug effects Oocytes - physiology Patch-Clamp Techniques Temperature Xenopus laevis |
| title | Kinetics and Stoichiometry of a Proton/myo-Inositol Cotransporter |
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