Dosage compensation equalizes the expression of sex-linked genes between males and females. Most genes on the X chromosome of male @entity238 are transcribed at an increased level, contributing to compensation. The @entity68092 and @entity65122 genes produce non-coding transcripts that localize along the X-chromosome of male flies. Although lacking sequence similarity, they are necessary but redundant components of a system that up-regulates gene expression. Simultaneous mutation of both @entity65122 genes disrupts the X-limited distribution of proteins that modify chromatin to enhance gene expression. We have generated and characterized loss of function @entity68092 alleles that display a continuum of activity. Those that support intermediate male survival have strikingly reduced RNA accumulation, while alleles with minor contributions to male viability typically lack detectable transcript accumulation. Severely mutated @entity68092 alleles retain some ability to direct modifying proteins to the X chromosome. This ability predicts the level of male survival that each allele supports. This points to a peripheral or transient role for @entity65122 in the RNA and protein complex that binds to and regulates the X chromosome.

The severity of XXXX mutations is predicted by MSL localization on the X chromosome.

@entity68092 :: ('3772376(Tax:7227)', 'Gene') :: ['roX1'] @entity65122 :: ('3772415(Tax:7227)', 'Gene') :: ['roX', 'roX2'] @entity238 :: ('7227', 'Species') :: ['Drosophila']
@entity68092 :: (3772376(Tax:7227),Gene) :: ['roX1']
