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

Abstract

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.

Characterization of the deoxyhemoglobin binding site on human erythrocyte band 3: implications for O2 regulation of erythrocyte properties

“…[2][3][4][30][31][32][33][34] The question therefore arises whether the deoxyHb binding sequence on human band 3 might be conserved in these other species. Although amino acid insertions and deletions frequently occur near the NH 2 -termini of all band 3 homologs, a region of high homology can nevertheless be identified in mammalian and avian sequences 35 but not in the sequences of fish (rainbow trout and zebrafish) band 3 homologs (Figure 7). Perhaps consistent with these observations, O 2 regulation of ion transport in mammalian and avian species exhibits an O 2 concentration dependence that follows the O 2 dissociation curve of Hb.…”

Two chicken erythrocyte band 3 mRNAs are generated by alternative transcriptional initiation and differential RNA splicing.

“…The probe was prepared by labeling at the 5' end of the antisense DNA strand with T4 polynucleotide kinase in the presence of [.y-32P]ATP. A 5-to 10-,ug amount of total chicken erythroid RNA was used per reaction, and hybridizations were carried out as previously described (30,49). The plasmid and restriction enzymes used to prepare the probe, hybridization temperature, Si nuclease concentration, and Si digestion temperature are described in Results and the figure legends.…”

“…Unamplified chicken XEMBL3 and XEMBL4 genomic libraries (30) were plated at a density of 5 x 104 PFU/150-mm-diameter petri plate on host strain Escherichia coli 803 supF. Plaque filter screening was performed as previously described (2,17).…”

“…We recently showed that a single genetic locus for chicken erythrocyte band 3 is capable of encoding two different mRNAs (as represented by the cDNA clones XBIIIC1 and XBIIIC2 [30]) with different translation initiation sites. These two cDNA clones predict the existence of polypeptides with molecular weights of ca.…”

“…In addition to the TATA and CCAAT boxes, a variety of upstream promoter elements and distal regulatory elements (enhancers and silencers), each containing distinct recognition sequences corresponding to the binding sites for transcriptional regulatory factors, have been shown to elevate or depress the rate of transcription from a given promoter (6,35,42). Given the litany of curious inferences about transcriptional regulation in both the murine and chicken erythrocyte band 3 genes, and since band 3 (30).…”