Fig. 6

A model of chromatin fragment interactions. a Interpretation of the ChAs results for RNAPII and RNAPII-S2P with a cartoon network in which we highlight P–P and P–O contacts. The elongating variant RNAPII-S2P is associated with active enhancers which contact promoters that might also contact each other. This situation corresponds to equally high ChAs in both types of contacts. Other forms of RNAPII (lacking S2 phosphorylation) have lower ChAs in P–O contacts but high ChAs in P–P contacts. b Virtual-4C (extraction of interactions centered on a specific genomic location from genome-wide data) anchored on the HOXA1 promoter showing P–P and P–O contacts and corresponding peaks of different RNAPII variants. c A model of loops formed between distal regulatory elements, promoters, and gene bodies bound by RNAPII-S2P