Islation and characterization of steroid sulfate conjugate transporter (SSCT) in Chinese fluk (Clonorchis sinensis)

초록

To consume raw or undercooked freshwater fish containing metacercaria of Chinese fluke is the primary cause of clonorchiasis. The long term infection of liver fluke has been shown, both experimentally and epidemiologically, to cause chronic pathological changes, such as cholangitis, cholecystitis, hepatomegaly, hepatic fibrosis, and cholangiocarcinoma. The target gene was isolated using cDNA library screening and Xenopus oocyte expression system was employed for functional analysis. The open reading frame of SSCT cDNA consist of 1641 base pairs that encoded a 546-amino acid residue protein. Hydropathy analysis suggested that SSCT possess 10 putative membrane-spanning domains. When expressed in Xenopus oocytes, SSCT mediated the transport of radiolabeled estrone sulfate in a time- and sodium-dependent manner. There were no uptake of bile acid (taurocholic acid), organic anion and cation transporter substrate (p-aminohippuric acid and tetraethyl ammonium), respectively. The SSCT showed no antiport or cotransport properties by efflux experiments. From above results, this transporter protein is steroid sulfate conjugate transporter but not bile acid transporter.