title: Dosage compensation in mammals: why does a gene on the inactive X yield less product than one on the active X?
abstract: An expressed gene on the inactive mammalian X chromosome yields less product than the same gene on the active X. Characteristics of the inactive X which might be responsible for this are late replication, chromatin clumping, and altered patterns of DNA methylation. If an expressed gene on the inactive X is not replicated until late in S, it will be present in two copies for a shorter fraction of the cell cycle than its early replicating homologue and therefore yield less product. Alternatively, transcription may be slowed by a microenvironment of highly condensed chromatin or by an abnormal pattern of methylation of the DNA template. Experiments are proposed by which to test these and related hypotheses.
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D004261:DNA Replication; D004303:Dosage Compensation, Genetic; D005260:Female; D005796:Genes; D005819:Genetic Markers; D006801:Humans; D014960:X Chromosome
chemical_list: D005819:Genetic Markers