MOF, A PUTATIVE ACETYL TRANSFERASE GENE-RELATED TO THE TIP60 AND MOZ HUMAN GENES AND TO THE SAS GENES OF YEAST, IS REQUIRED FOR DOSAGE COMPENSATION IN DROSOPHILA

Dosage compensation is a regulatory process that insures that males an d females have equal amounts of X-chromosome gene products, In Drosoph ila, this is achieved by a 2-fold enhancement of X-linked gene transcr iption in males, relative to females, The enhancement of transcription is mediated by the activity of a group of regulatory genes characteri zed by the male-specific lethality of their loss-of-function alleles, The products of these genes form a complex that is preferentially asso ciated with numerous sites on the X chromosome in somatic cells of mal es but not of females, Binding of the dosage compensation complex is c orrelated with a significant increase in the presence of a specific hi stone isoform, histone 4 acetylated at Lys16, on this chromosome, Expe rimental results and sequence analysis suggest that an additional gene , males-absent on the first (mof), encodes a putative acetyl transfera se that plays a direct role in the specific histone acetylation associ ated with dosage compensation, The predicted amino acid sequence of MO F exhibits a significant level of similarity to several other proteins , including the human HIV-1 Tat interactive protein Tip60, the human m onocytic leukemia zinc finger protein MOZ and the yeast silencing prot eins SAS3 and SAS2.