The Drosophila melanogaster male dosage-compensation complex. The complex, called the MSL complex in Drosophila, consists of five proteins (MSL1, MSL2, MSL3, MOF, MLE) and two non-coding roX RNAs. The proteins, but not the roX RNAs, are evolutionarily conserved, as related proteins can be found in yeast and humans (for details see [30, 68, 69]). The box lists the conserved protein domains of the individual members of the Drosophila MSL complex and their identified functions for dosage compensation. MSL2 is the only male-specific protein subunit; all other subunits are present in both sexes. The two roX RNAs (see bottom of table) are also only expressed in males. The curved arrows symbolize the known enzymatic activities in the dosage-compensation complex. MLE is an RNA helicase that hydrolyzes ATP to effect conformational changes in DNA and RNA . MOF is a lysine acetyltransferase with specificity for lysine 16 of histone H4. Abbreviations of the protein domains are: CXC, cysteine-rich domain; ZnF, zinc finger; PEHE, proline-glutamic acid-histidine-glutamic acid; HAT, histone acetyltransferase; MYST, MOZ (monocytic leukemia zinc finger protein), YBF2/SAS3 (something about silencing 3), SAS2 and TIP60 (60 kDa Tat-interactive protein); MRG, mortality factor on chromosome 4 related gene and DExH, aspartic acid-glutamic acid-x-histidine.