Research Abstract |
We have obtained following results on a UDP-galactose transporter, a polyamine transporter, and a Na^+/H^+ antiporter, respectively. 1. Molecular cloning and characterization of UDP-galactose transporter (UGT). We have succeeded the molecular cloning of human UGT.UGT has shown to be two isoforms, hUGT1 and hUGT2, that are most likely generated through the alternative splicing of a transcript derived from the UGT gene. Introduction of the open reading frame sequence of hUGT into a mouse cell line, Had-1, that lacks UGT,complemented the genetic defect of the mutant, and the nucleotide-sugar transprting activity was detected in Goldi apparatus prepared from the transformant. These results suppoort the products of UGT cDNa to be the UDP-galactose transporter. 2. Polyamine transporter. Polarized LLC-PK,cells took up putrescine and spermidine from both apical and basolateral sides in a time- and temperature-dependent manner. Kinetic analyzes of the uptake of free polyamines suggest that a transporter with a high affinity for polyamines expressed preferentially on the apical surface of polarized LLC-PK_1 cells. The monoacetylated form of polyamines was taken up by the cells, while there was no sighn of the uptake of diacetylated derivatives. Na^+/H^+ antiporter (NHE). NHE1 was found in the basolateral side, while NHE3 located in the apical side of vobine kidney cortex.
|