SMALL MAF PROTEINS INTERACT WITH THE HUMAN TRANSCRIPTION FACTOR TCF11NRF1/LCR-F1/

The human TCF11 gene encodes a ubiquitously expressed bZIP transcripti on factor of the cap n' collar (CNC) domain family, It has a high sequ ence similarity to the erythroid-specific bZIP factor p45 NF-E2 in the CNC domain, which is involved in DNA binding. LCR-F1, a TCF11 isoform , is a more potent transcriptional activator than p45 NF-E2 in erythro id cells, We show here that the TCF11 protein interacts to form hetero dimers with small Maf proteins, previously shown to dimerize with p45 NF-E2, ECH and Fos, Such heterodimerization significantly alters the D NA binding characteristics of TCF11, While TCF11 alone binds in vitro to the tandem NF-E2 site derived from 5' DNase hypersensitive site 2 i n the beta-globin locus control region and to the single NF-E2 site in the porphobilinogen deaminase gene promoter, stronger binding is dete cted in the presence of small Maf proteins, Using antibodies, TCF11 is oforms bound to the single NF-E2 site were detected in K562 erythroid cell nuclear extracts. These findings place TCF11 as a good candidate for the proposed widely expressed factor(s) known to interact with sma ll Maf proteins and bind NF-E2 sites in a sequence-specific manner res embling NF-E2.