A newly discovered human α-globin gene

Abstract

AbstractA previously undefined transcript with significant homology to the pseudo-α2 region of the α-globin locus on human chromosome 16 was detected as part of an effort to better define the transcriptional profiles of human reticulocytes. Cloning and sequencing of that transcript (GenBank AY698022; named μ-globin) revealed an insert with a 423-nucleotide open reading frame. BLASTP and ClustalW and phylogenetic analyses of the predicted protein demonstrated a high level of homology with the avian α-D globin. In addition, the heme- and globin-binding amino acids of μ-globin and avian α-D globin are largely conserved. Using quantitative real-time polymerase chain reaction (PCR), μ-globin was detected at a level of approximately 0.1% that measured for α-globin in erythroid tissues. Erythroid-specific expression was detected by Northern blot analysis, and maximal expression during the erythroblast terminal differentiation was also detected. Despite this highly regulated pattern of μ-globin gene transcription, μ-globin protein was not detected by mass spectrometry. These results suggest the human genome encodes a previously unrecognized globin member of the avian α-D family that is transcribed in a highly regulated pattern in erythroid cells. (Blood. 2005;106:1466-1472)