Cloning and expression of a mammalian Na+/amino acid cotransporter with sequence similarity to Na+/glucose cotransporters
We describe the full-length sequence and functional expression of a cDNA cloned from LLC-PK1 cells, which appears to encode a mammalian Na(+)-dependent neutral amino acid transporter with properties characteristic of system A. This sequence, designated SAAT1, is 76% identical and 89% similar in amin...
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Published in | The Journal of biological chemistry Vol. 268; no. 3; pp. 1509 - 1512 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Bethesda, MD
American Society for Biochemistry and Molecular Biology
25.01.1993
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Subjects | |
Online Access | Get full text |
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Summary: | We describe the full-length sequence and functional expression of a cDNA cloned from LLC-PK1 cells, which appears to encode
a mammalian Na(+)-dependent neutral amino acid transporter with properties characteristic of system A. This sequence, designated
SAAT1, is 76% identical and 89% similar in amino acid sequence to the Na(+)-dependent glucose transporter SGLT1 of the same
species. A leucine zipper region was detected in both SAAT1 and SGLT1. The message for SAAT1 was a single 2.4-kilobase species
in kidney, but mRNA species of 2.4 and 3.7 kilobases were observed in LLC-PK1 cells as well as in intestine. Transcripts were
also found in spleen, liver, and muscle. Expression of SAAT1 in COS-7 cells resulted in increased levels of Na(+)-dependent
uptake of 2-(methylamino)isobutyric acid, a specific substrate for the system A amino acid transporter. Uptake due to cDNA
expression was inhibited by a range of amino acids that are transported by system A and exhibited a km of 0.8 +/- 0.2 mM.
These results suggest that the system A amino acid transporter is closely related to the Na+/glucose transporter SGLT1. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(18)53880-1 |