The Yaf9 component of the SWR1 and NuA4 complexes is required for proper gene expression, histone H4 acetylation, and Htz1 replacement near telomeres.

Yaf9, Taf14, and Sas5 comprise the YEATS domain family in Saccharomyces cerevisiae, which in humans includes proteins involved in acute leukemias. The YEATS domain family is essential, as a yaf9Delta taf14Delta sas5Delta triple mutant is nonviable. We verify that Yaf9 is a stable component of NuA4, an essential histone H4 acetyltransferase complex.