A membrane-located polypeptide of Ulva sp. which may be involved in HCO3- uptake is recognized by antibodies raised against the human red-blood-cell anion-exchange protein.

Polypeptides present in a membrane fraction of the marine macroalga Ulva sp. were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and tested for cross-reactivity with antibodies raised against the human red-blood-cell anion exchanger (AE1). A polypeptide of ca. 95 kDa was identified with a monoclonal, as well as two polyclonal (one against the C-terminus and one against the whole protein) antibodies, indicating that it shares homologous domains with AE1. These findings complement an earlier study which indicated that a plasmalemma-bound, disulfonic stilbene-sensitive, protein was functionally involved in HCO3- transport into the photosynthesizing cells of Ulva (Z. Drechsler et al. 1993, Planta 191, 34-40). It is thus suggested here that a similar protein has evolved, and has been conserved, in marine photosynthetic organisms and mammalian red blood cells for the purpose of HCO3- transport.