Functions as component of the ISW1B complex, which acts in remodeling the chromatin by catalyzing an ATP-dependent alteration in the structure of nucleosomal DNA. The ISW1B complex acts within coding regions to control the amount of RNA polymerase II released into productive elongation and to coordinate elongation with termination and pre-mRNA processing. Component of the ISW1B complex, which at least consists of ISW1, IOC2 and IOC4. Present with 5820 molecules/cell in log phase SD medium.