Nuclear protein factors anderythroid transcription ofthehumanAy-globin gene

WehaveusedDNaseIfoot printing andgelmobility assaystoanalyze the upstream region ofthehumanM-globin genepromoter. Fourprotein factors werefoundtobindthisregion.Anon-erythroid factor present inthe0.4M KClfraction ofaheparin agarose column bindstotheCACbox(-140).A ubiquitous octamer factor present inthe0.2Mfraction bindstoanATGCAAT element (-175), butiscompeted outbytheerythroid specific factor NF-E1 (inthe0.4MKC1fraction), whichbindsasite(-186) immediately flanking theoctamer.A novelfactor binding toastretch of8Aaround -233, was identified inthe0.2MKC1fraction. Thisfactor isnotpresent inHeLa nuclear extracts. Tostudythetranscriptional importance oftheseprotein binding siteswehaveusedan"A-f-minilocus", similar tothatdescribed for thef-globin gene(1)inK562cells. Thisprovides evidence thattheNF-E1 andCACboxinthe-210to-122region ofthe _y-promoter areimportant for theefficient expression ofthey-globin gene.