## Publications : 2001

Yoon M, Jung H, Lee H, Park T. 2001. Beta-alanine induced down-regulation of the taurine transporter activity in the human colon carcinoma cell line (HT-29). J Korean Soc Food Sci Nutr 30(2):314–319.

## Abstract

In the present study, effects of $small{beta}$-alanine, a known taurine antagonist for its structural similarity, on the adaptive regulation and kinetic behavior of the taurine transporter were investigated in the HT-29, human colon carcinoma cell line. Pretreatment of the cell with $small{beta}$-alanine(10mM) for varying periods from 3 to 30 hrs significantly reduced the taurine uptake compared to the value for control cells. This decrease in the taurine transporter activity was dependent on the incubation time with $small{beta}$-alanine, and the maximal down-regulation of the transporter activity was observed in cells pretreated with $small{beta}$-alanine for 24 hrs (25% of the control value, p<0.01). The taurine transporter appears to bind exclusively with $small{beta}$-alanine in the HT-29 cells since the same concentration of $small{alpha}$-alanine added in the culture medium for 24 hrs did not influence the taurine uptake. Kinetic analyses of the taurine transporter activity was performed in the HT-29 cell line with varying taurine concentration (5~60$small{mu}$M) in the uptake medium. Active taurine uptake was significantly lower in $small{beta}$-alanine pretreated cells compared to the value for control cells in the range of taurine concentration used in the experiment (p<0.001). The cells pretreated with $small{beta}$-alanine showed a 50% lower maximal velocity (Vmax, 1.7$small{pm}$2.0 nmole.mg $small{protein^{-1}}$.$small{30min^{-1}}$), and a 99% higher Michaelis constant (Km, 40.3$small{pm}$7.6$small{mu}$M) than the control values (3.3$small{pm}$1.9 nmole.mg $small{protein^{-1}}$.$small{30min^{-1}}$, and 20.3$small{pm}$2.1$small{mu}$M, respectively). These results on kinetic data suggest that $small{beta}$-alanine induced down-regulation of the taurine transporter activity was associated with decreases in both maximal velocity and affinity of the transporter.