The PWWP domain is a component of the S. pombe hypothetical protein SPBC215, as well as ISWI complex protein 4. The ISWI (imitation switch) proteins are ATPases responsible for chromatin remodeling in eukaryotes, and SPBC215 is proposed to also bind chromatin. The PWWP domain, named for a conserved Pro-Trp-Trp-Pro motif, is a small domain consisting of 100-150 amino acids. The PWWP domain is found in numerous proteins that are involved in cell division, growth and differentiation. Most PWWP-domain proteins seem to be nuclear, often DNA-binding, proteins that function as transcription factors regulating a variety of developmental processes.