Activation of FUSE, the far-upstream element, is required for the proper expression of the mammalian gene c-myc. The binding of FBP (FUSE-binding protein) to FUSE is necessary for c-myc expression. The FBP interacting repressor, FIR, binds to the central DNA-binding domain of FBP and can serve as an overriding negative regulator of c-myc promoter activity. FIR interacts with the TFIIH complex, which is a multifunctional, multisubunit RNA polymerase II transcription factor that interacts with several DNA-binding transactivators. FIR blocks activator-dependent, but not basal transcription through TFIIH. FIR shares identity with seven in absentia (siah) binding protein 1. FIR is expressed in spleen, thymus, prostate, small intestine, colon, and peripheral blood leukocytes, and with relatively higher levels of expression in testis and ovary.