Fig. 4.

A model for repression of prespliceosome complex formation by the Fox-1 family. The repression of calcitonin-specific exon 4 of calcitonin/CGRP pre-mRNA in neuronal cells by the Fox-1 family involves two distinct regulatory events. First, the −34 element in the UIF region prevents E′ complex formation through repressing SF1 binding to the branch point (B). Second, the +45 exonic element blocks transition to E complex via inhibiting U2AF⁶⁵ binding to polypyrimidine tract (PY). This figure is modified from [49]