Further studies on bilitranslocase, a plasma membrane protein involved in hepatic organic anion uptake

Physicochemical and immunohistological studies of a sulfobromophthalein- and bilirubin-binding protein from rat liver plasma membranes.

“…2 Tiribelli et al (12) have described another BSPbinding protein, designated bilitranslocase. Initially isolated in the presence of deoxycholate, and reported to have a molecular mass of 170,000 D, omission of deoxycholate has subsequently led to a lower molecular mass estimate of -100,000 D (50). The latter protein can be resolved by reduction and SDS into two nonidentical subunits, a (molecular mass 37,000 D) and # (molecular mass 35,500 D).…”

“…The latter protein can be resolved by reduction and SDS into two nonidentical subunits, a (molecular mass 37,000 D) and # (molecular mass 35,500 D). An overall subunit composition a2f3 has been proposed (50). Any relationship between bilitranslocase and the BSP/bilirubin receptor protein described above remains to be established.…”

Hepatocellular uptake of sulfobromophthalein and bilirubin is selectively inhibited by an antibody to the liver plasma membrane sulfobromophthalein/bilirubin binding protein.

“…The relation if any, ofthese proteins to the "bilitranslocase" reported by Tiribelli and associates (33) remains to be established. The most recently reported subunit structure and molecular weight estimates (34) suggest, that they are in fact unrelated. The reported inhibition ofBSP transport in the isolated perfused rat liver by an antibody to bilitranslocase (35) lacked evidence of specificity and any investigation of antibody toxicity, which we have found to be a significant problem with some antibody preparations in studies of this type.…”

Influence of Cl- on organic anion transport in short-term cultured rat hepatocytes and isolated perfused rat liver.

“…10 Mul of stock solution was added to 1 ml of media on each plate (0.8 MM final concentration) and incubation was continued at 4 or 37°C for various times. After incubation with [35S]BSP, plates were washed twice at 4°C with 1.5 ml of SFM.…”

“…Countertransport and a preloading effect have been reported (1), and the uptake mechanism is believed to be one of facilitated diffusion. Although several candidate transport proteins have been proposed (8)(9)(10)(11), the identity of the putative carrier is not clear.…”