FUNCTIONAL REASSEMBLY OF THE ANION TRANSPORT DOMAIN OF HUMAN RED-CELLBAND-3 (AE1) FROM MULTIPLE AND NON-COMPLEMENTARY FRAGMENTS

We constructed cDNA clones encoding N-terminal, C-terminal and interna l polypeptide fragments of the human red cell anion exchanger (band 3; AE1), The internal fragments comprised between one and seven putative transmembrane spans with two or more spans deleted from both termini of the membrane domain of band 3. Sets of three, four or five compleme ntary fragments, which together represented the complete amino acid se quence of the membrane domain, were co-expressed in Xenopus oocytes, S tilbene disulphonate-sensitive chloride uptake assays revealed that al l six of the three-fragment combinations and two of the four-fragment combinations reassembled functionally in vivo. Unexpectedly, co-expres sion of a non-complementary pair of fragments comprising the first fiv e and last seven putative transmembrane spans (i.e. entirely lacking s pans six and seven) was also found to be sufficient to generate stilbe ne disulphonate-sensitive chloride uptake. (C) 1998 Federation of Euro pean Biochemical Societies.