Cloning and characterization of the transport modifier RS1 from rabbit which was previously assumed to be specific for Na +- d-glucose cotransport

• Published in: Biochimica et biophysica acta 1999-02, Vol.1417 (1), p.131-143
• Main Authors: Reinhardt, Jürgen, Veyhl, Maike, Wagner, Katharina, Gambaryan, Stepan, Dekel, Carmela, Akhoundova, Aida, Korn, Thomas, Koepsell, Hermann
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Carrier Proteins - biosynthesis; Carrier Proteins - chemistry; Carrier Proteins - genetics; Cation Transport Proteins; Cloning, Molecular; DNA, Complementary - genetics; Expression; Humans; Intestine, Small - metabolism; Kidney - metabolism; Membrane Glycoproteins - biosynthesis; Membrane Glycoproteins - genetics; Molecular Sequence Data; Monosaccharide Transport Proteins - biosynthesis; Monosaccharide Transport Proteins - genetics; Na +- d-Glucose cotransporter SGLT1; Oocytes - metabolism; Organic cation transporter OCT2; Primary structure; Rabbit; Rabbits; RNA, Messenger - analysis; Sequence Alignment; Sodium-Glucose Transporter 1; Species Specificity; Symporters; Transport modifier RS1; Xenopus laevis
• ISSN: 0005-2736; 0006-3002; 1879-2642
• DOI: 10.1016/S0005-2736(98)00250-8

Previously we cloned membrane associated polypeptides from pig and man (pRS1, hRS1) which altered rate and glucose dependence of Na +- d-glucose cotransport expressed by SGLT1 from rabbit and man. This paper describes the cloning of a related cDNA sequence from rabbit intestine ( rbRS1) which encodes a gene product with about 65% amino acid identity to pRS1 and hRS1. Hybridization of endonuclease-restricted genomic DNA with cDNA fragments of rbRS1 showed that there is only one gene with similarity to rbRS1 in rabbit, and genomic PCR amplifications revealed that the rbRS1 gene is intronless. Comparing the transcription of rbRS1 and rbSGLT1 in various tissues and cell types, different mRNA patterns were obtained for both genes. In Xenopus oocytes the V max of expressed Na +- d-glucose cotransport was increased or decreased when rbRS1 was coexpressed with rbSGLT1 or hSGLT1, respectively. After coexpression with hSGLT1 the glucose dependence of the expressed transport was changed. By coexpression of rbRS1 with the human organic cation transporter hOCT2 the expressed cation uptake was not altered; however, the expressed cation uptake was drastically decreased when hRS1 was coexpressed with hOCT2. The data show that RS1 can modulate the function of transporters with non-homologous primary structures.