Reconstitution of sulfobromophthalein transport in erythrocyte membranes induced by bilitranslocase.

Bilitranslocase, the protein responsible for the anion translocation at the sinusoidal plasma membrane level in liver, was shown to be able to reconstitute the transport of sulfobromophthalein in liposomes in the past. The protein preparation used in those experiments consisted of two subunits of 35.5 and 37 kDa. The isolated 37 kDa protein, when inserted in erythrocyte membrane vesicles, confers to the particles the ability to carry out an electrogenic transport of sulfobromophthalein. The effect is specific and can be inhibited by monospecific polyclonal antibodies raised against the protein. In may be concluded that the 37 kDa protein band, present in previous preparations of bilitranslocase, is not only a necessary but also a sufficient component of the transport system for bilirubin and functional analogues.