Rel homology <p>The Rel homology domain (RHD) is found in a family of eukaryotic transcription factors, which includes NF-kappaB, Dorsal, Relish, NFAT, among others. Some of these transcription factors appear to form multi-protein DNA-bound complexes [<cite idref="PUB00016328"/>]. Phosphorylation of the RHD appears to play a role in the regulation of some of these transcription factors, acting to modulate the expression of their target genes [<cite idref="PUB00016329"/>]. The RHD is composed of two immunoglobulin-like beta-barrel subdomains that grip the DNA in the major groove. The N-terminal specificity domain resembles the core domain of the p53 transcription factor, and contains a recognition loop that interacts with DNA bases; the C-terminal dimerisation domain contains the site for interaction with I-kappaB [<cite idref="PUB00004201"/>].</p>