Characterization of the gene for the human high affinity IgE receptor (Fc[epsilon]RI) [alpha]-chain

The Fc[epsilon]RI couples the mast cell-surface binding of IgE and Ag to a complex series of intracellular events culminating in cell activation and degranulation. The [alpha]-chain of Fc[epsilon]RI constitutes the Ig-binding subunit of this heterotetrameric receptor, and is itself a member of the Ig gene superfamily. The authors have isolated a human genomic DNA clone containing the entire Fc[epsilon]RI[alpha] gene, and completely sequenced a region from 1257 bp 5[prime] of the transcription start site, to 513 bp 3[prime] of the last exon of the gene. As with the previously characterized rat and mouse genes, human Fc[epsilon]RI[alpha] consists of five exons and four introns, and spans 5889 bp of genomic DNA. The splice donor and acceptor sites deduced by comparison with the cDNA sequence corresponded exactly to the locations found in analogous rodent genes. By mapping the 5[prime] end of Fc[epsilon]RI[alpha] transcripts they found three major transcription initiation sites 24, 27, 29 bp upstream of the ATG translation initiation codon. About 650 bp of DNA upstream of the ATG translation initiation codon were compared among human, rat, and mouse Fc[epsilon]RI[alpha] sequences in search of common motifs that might mediate conserved regulatory interactions with DNA binding proteins. A 172-bp region of the human Fc[epsilon]RI[alpha] 5[prime]-flanking sequence was highly conserved in both rodent species. Further studies will be required to determine whether these or other sequences are involved in Fc[epsilon]RI[alpha] gene regulation.