The Msl proteins are essential for elevating transcription of the single X chromosome in the male (X chromosome dosage compensation). Msl-2 is required for translation and/or stability of msl-1 in males. In complex with msl-1, acts as an E3 ubiquitin ligase that promotes ubiquitination of histone H2B. Component of the male-specific lethal (MSL) histone acetyltransferase complex at least composed of mof, msl-1, msl-2 and msl-3. Msl-1 and msl-2 colocalize to many sites on the male X chromosome. Only produced in males. Belongs to the MSL2 family.