Resolution:
## Figure 2.
Statistical model of RPol II distribution of Bi-peak shape. (A) RPol II binding fragments on 2 promoters form a bi-peak shape. Green and blue
dotted lines represent the RPol II distribution surrounding TSSs of 2 opposite genes.
The red line presents the accumulation of RPol II fragments. P1, P2, and V are 3 features
of the bi-peak shape. The parameters, Sig and Dif, are used to identify the bi-peak
shape of RPol II distribution in bidirectional regions.(B) A statistical model of
RPol II binding pattern surrounding theTSSs of bi-directional gene pairs. The adjacent
genomic regions are divided into multiple 20-bp bins, in which the number of RPol
II fragments is assumed to follow a Poisson distribution for each promoter. For each of these, the overall binding pattern coud
be characterized by 5 hidden variables, including 3 variables describing the expected
number of fragments in the background region (B), the transcript region (T), and the
bin that contains TSS (S), and 2 variables modeling the signal decay rates in both
upstream and downstream of the TSS (K_{p }and K_{t}). Each hidden variable follows a gamma distribution genome-wide. For the accumulation
of RPol II fragments of two promoters, the number of RPol II fragments also follow
a Poisson distribution.
Wang |