Molecular isolation and characterization of choline transporter in Clonorchis sinensis

초록

Choline is an essential nutrient for humans and many other animals. To maintain their health, choline must be obtained from the food as choline or as choline phospholipids (phosphatidylcholine). Choline phospholipids are necessary components in cell membranes in most animals. It is required to produce acetylcholine (a neurotransmitter) and S-adenosylmethionine (a methyl group donor). From NCBI database, the target high-affinity choline transporter (CsCT, RJW67685.1) was isolated using reverse-transcription polymerase chain reaction. The open reading frame of CsCT cDNA consists of 1710 base pairs that encoded a 569-amino acid residue protein (expected molecular weight; 62700 Da). Hydropathy analysis suggested that CsCT possesses 12 putative membrane-spanning domains. When expressed in Xenopus laevis oocytes, CsCT mediated the transport of radiolabeled choline in an expression time-, incubation time- and sodium-dependent manner. The homology compared with other fluke-related proteins showed 63 ? 71% identity. These results showed that the choline transporter exists in Clonorchis sinensis. It might give some clue to us on choline metabolism and signal transduction cascades.