The DDT domain is named after (DNA binding homeobox and Different Transcription factors) and is approximately 60 residues in length [1]. Along with the WHIM motifs, it comprises an entirely alpha helical module found in diverse eukaryotic chromatin proteins [2]. Based on the structure of Ioc3, this module is inferred to interact with nucleosomal linker DNA and the SLIDE domain of ISWI proteins [2][3]. The resulting complex forms a protein ruler that measures out the spacing between two adjacent nucleosomes [2]. In particular, the DDT domain, in combination with the WHIM1 and WHIM2 motifs form the SLIDE domain binding pocket [2].

1: DDT -- a novel domain in different transcription and chromosome remodeling factors. Doerks T, Copley R, Bork P; Trends Biochem Sci 2001;26:145-146. PMID:11246006

2: The HARE-HTH and associated domains: novel modules in the coordination of epigenetic DNA and protein modifications. Aravind L, Iyer LM; Cell Cycle. 2012;11:119-131. PMID:22186017

3: Structure and mechanism of the chromatin remodelling factor ISW1a. Yamada K, Frouws TD, Angst B, Fitzgerald DJ, DeLuca C, Schimmele K, Sargent DF, Richmond TJ; Nature. 2011;472:448-453. PMID:21525927