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Isolation and function of the amino acid transporter PAT1 (SLC36A1) from rabbit and discrimination between transport via PAT1 and system IMINO in renal brush-border membrane vesicles

Lookup NU author(s): Dr Emily Abbot, Professor David Thwaites

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Abstract

Reabsorption of amino acids is an important function of the renal proximal tubule. pH-dependent amino acid transport has been measured previously using rabbit renal brush-border membrane vesicles (BBMV). The purpose of this investigation was to determine whether this pH-dependent uptake represents H+/amino acid cotransport via a PAT1-like transport system. The rabbit PAT1 cDNA was isolated (2296bp including both 5′ and 3′ untranslated regions and poly(A) tail) and the open reading frame codes for a protein of 475 amino acids (92% identity to human PAT1). Rabbit PAT1 mRNA was found in all tissues investigated including kidney. When expressed heterologously in a mammalian cell line, rabbit PAT1 mediates pH-dependent, Na+-independent uptake of proline, glycine, L-alanine and α-(methylamino)isobutyric acid. Proline uptake was maximal at pH 5.0 (Km 2.2 ± 0.7 mM). A transport system with identical characteristics (ion dependency, substrate specificity) was detected in rabbit renal BBMV where an overshoot was observed in the absence of Na+ but in the presence of an inwardly directed H+ gradient. In the presence of Na+ and under conditions in which PAT1 transport function was suppressed, a second proline uptake system was detected that exhibited functional characteristics similar to those of the IMINO system. The functional characteristics of rabbit PAT1 in either mammalian cells or renal BBMV suggest that PAT1 is the low-affinity transporter of proline, glycine and hydroxyproline believed to be defective in patients with iminoglycinuria. © 2005 Taylor & Francis.


Publication metadata

Author(s): Miyauchi S, Abbot EL, Zhuang L, Subramanian R, Ganapathy V, Thwaites DT

Publication type: Article

Publication status: Published

Journal: Molecular Membrane Biology

Year: 2005

Volume: 22

Issue: 6

Pages: 549-559

ISSN (print): 0968-7688

ISSN (electronic): 1464-5203

Publisher: Informa Healthcare

URL: http://dx.doi.org/10.1080/09687860500421779

DOI: 10.1080/09687860500421779

PubMed id: 16373326


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