Stable inducible expression of a functional rat liver organic anion transport protein in HeLa cells.
Recently we expression cloned a rat liver organic anion transport protein in Xenopus laevis oocytes (Jacquemin, E. Hagenbuch, B, Stieger, B., Wolkoff, A.W., and Meier, P.J.,(1994) Proc. Natl. Acad. Sci. U.S.A. 91, 133-137). In the present study, we have stably transfected the cDNA encoding this protein into HeLa cells by using a vector containing a zinc-inducible promoter. The parent cells have virtually no baseline transport of [35S]sulfobromophthalein, whereas the induced transfected cells express a novel 74-kDa protein and avidly transport this ligand. Transport by these cells is saturable (Km = 3.3 microM, Vmax = 257 pmol/min/mg protein), bidirectional, and highly temperature-dependent. In the presence of albumin, uptake of [35S]sulfobromophthalein requires the presence of extracellular Cl, whereas in the absence of albumin, this C1- dependence is not seen. These studies indicate that cellular uptake of sulfobromophthalein does not result from direct interaction with the plasma membrane lipid bilayer but rather requires the presence of a specific plasma membrane transporter.
Shi
X
X
Marion Bessin Liver Research Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
Bai
S
S
Ford
A C
AC
Burk
R D
RD
Jacquemin
E
E
Hagenbuch
B
B
Meier
P J
PJ
Wolkoff
A W
AW
D000418:Albumins / Q000494:pharmacology; D000818:Animals; D027321:Anion Transport Proteins; D001692:Biological Transport; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D008099:Liver / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis; D013448:Sulfobromophthalein / Q000378:metabolism*; D014162:Transfection; D015032:Zinc / Q000494:pharmacology
D000418:Albumins; D027321:Anion Transport Proteins; D002352:Carrier Proteins; D011994:Recombinant Proteins; D013448:Sulfobromophthalein; D015032:Zinc