Two different mRNAs are transcribed from a single genomic locus encoding the chicken erythrocyte anion transport proteins (band 3).

The chicken erythrocyte anion transport protein (band 3 of the erythrocyte cytoskeleton) is a central component taking part in two widely divergent functions of erythroid cells; it is a primary determinant of cytoskeletal architecture and responsible for electroneutral Cl-/HCO3- exchange across the plasma membrane. To analyze interesting aspects of the developmental regulation of this gene, we have cloned the cDNA and genomic counterparts of the erythroid-specific anion transport protein. We show that a single genetic locus for band 3 encodes two different erythroid cell-specific mRNAs, with different translational initiation sites, which predict polypeptides of sizes very close to those observed in vivo. In vitro translation and immune precipitation of synthetic mRNA derived from one putative fully encoding cDNA clone demonstrate that this clone gives rise to a protein which is identical in size and antigenicity to bona fide chicken erythroid band 3.