Cloning and Functional Characterization of Human Sodium-dependent Organic Anion Transporter (SLC10A6)

Abstract

We have cloned human sodium-dependent organic anion transporter (SOAT) cDNA, which consists of 1502 bp and encodes a 377-amino acid protein. SOAT shows 42% sequence identity to the ileal apical sodium-dependent bile acid transporter ASBT and 33% sequence identity to the hepatic Na ؉ / taurocholate-cotransporting polypeptide NTCP. Immunoprecipitation of a SOAT-FLAG-tagged protein revealed a glycosylated form at 46 kDa that decreased to 42 kDa after PNGase F treatment. SOAT exhibits a seven-transmembrane domain topology with an outside-to-inside orientation of the N-terminal and C-terminal ends. SOAT mRNA is most highly expressed in testis. Relatively high SOAT expression was also detected in placenta and pancreas. We established a stable SOAT-HEK293 cell line that showed sodium-dependent transport of dehydroepiandrosterone sulfate, estrone-3-sulfate, and pregnenolone sulfate with apparent K m values of 28.7, 12.0, and 11.3 M, respectively. Although bile acids, such as taurocholic acid, cholic acid, and chenodeoxycholic acid, were not substrates of SOAT, the sulfoconjugated bile acid taurolithocholic acid-3-sulfate was transported by SOAT-HEK293 cells in a sodium-dependent manner and showed competitive inhibition of SOAT transport with an apparent K i value of 0.24 M. Several nonsteroidal organosulfates also strongly inhibited SOAT, including 1-(-sulfooxyethyl)pyrene, bromosulfophthalein, 2-and 4-sulfooxymethylpyrene, and ␣-naphthylsulfate. Among these inhibitors, 2-and 4-sulfooxymethylpyrene were competitive inhibitors of SOAT, with apparent K i values of 4.3 and 5.5 M, respectively, and they were also transported by SOAT-HEK293 cells.

The amyloid precursor protein intracellular domain alters gene expression and induces neuron-specific apoptosis

“…3). Hes5 encodes a transcription factor which plays an essential role in neurogenesis (Kageyama et al, 2007) and Slc10a6 encodes a protein that transports sulfoconjugated steroid hormones, as well as taurolithocholic acid-3-sulfate and sulfoconjugated pyrenes (Geyer et al, 2007). Several genes, such as Nid1 (extracellular matrix linker protein) (Mann et al, 1989), and LOC213332 (putative glucose transporter) (Horiba et al, Fig.…”

The STM4195 Gene Product (PanS) Transports Coenzyme A Precursors in Salmonella enterica

“…Until now, the study of SBF family proteins, including SLC10 family members, has focused largely on the contribution these transporters make to the metabolism of bile acids and structurally related steroidal compounds, including cholesterol. Several SBF family proteins have been viewed as promising drug targets for cholesterol-lowering treatment (40). Our work highlights the need to consider alternative solutes that may serve as the substrates for these transporters in various contexts.…”

Transporters

“…Kemp G, Young H, Fliegel L (2008). Structure and function of the human Na (Meier et al, 1997) Thyroid hormone (Friesema et al, 1999;Visser et al, 2010) GDCA > GUDCA, GCDA > TCA > CA (Craddock et al, 1998) Estrone-3-sulphate, DHEAS (Geyer et al, 2004), TLCA, PREGS (Geyer et al, 2007) Inhibitors Cyclosporin, propranolol (Kim et al, 1999) --Probes Chenodeoxycholyl-N e -nitrobenzoxadiazollysine (Weinman et al, 1998) [ 3 H]-Taurocholate (Craddock et al, 1998) Stoichiometry 2 Na + : 1 bile acid (Hagenbuch and Meier, 1996;Weinman, 1997) >1 Na + : 1 bile acid (Craddock et al, 1998) Heterologously expressed SLC10A4 (Geyer et al, 2008) or SLC10A7 (Godoy et al, 2007) failed to exhibit significant transport of TCA, PREGS, DHEAS or choline. SLC10A4 has recently been suggested to associate with neuronal vesicles (Burger et al, 2011).…”