Fig. 6.

Working model. (A) During wild-type CM differentiation, housekeeping genes and heterochromatic regions have dynamic H2Bub1 levels. H2Bub1 is sparsely maintained during the transition from cardiac mesoderm to cardiac progenitor. Notably, selectively maintained genes are enriched for calcium-signaling genes. (B) Genes that are short in length have an increase in H2Bub1 at their 5′ end that decreases towards the 3′ end. However, longer tissue-specific genes have an accumulation in H2Bub1 near the center of the gene in wild-type cells but not in UBE2B^−/−. In the mutants, when this accumulation is absent, the amount of full-length transcript is reduced.