Chromatin remodeler that regulates various aspects of transcription; acts in conjunction with Isw1b to regulate chromatin structure, maintain chromatin integrity during transcription elongation by RNAP II by preventing trans-histone exchange over coding regions; component of both SAGA and SLIK complexes; ATPase motor stimulates DNA unwrapping from nucleosomes; contains two chromodomains, a helicase domain and a DNA-binding domain; human ortholog CHD1 is a prostate cancer tumor suppressor