TRANSCRIPTION FACTOR NUCLEAR FACTOR-I PROTEINS FORM STABLE HOMODIMERSAND HETERODIMERS

Nuclear factor I (NFI) proteins constitute a large family of eukaryoti c DNA binding proteins. They are involved in viral and cellular aspect s of transcriptional regulation and they are capable of stimulating ad enovirus initiation of replication. Using in vitro translated NFI prot eins encoded by four different chicken NFI genes, we have detected hom odimers as well as heterodimers for all combinations tested. The forma tion of heterodimers was critically dependent on cotranslation, indica ting stable dimer formation in the absence of DNA. The unrestricted he terodimerization of NFI proteins adds, beside gene diversity and alter native splicing, another level of diversity to this protein family.