Scaffold protein that functions as a component of a multimolecular complex involved in histone mRNA 3'-end processing. Specific component of the tight junction (TJ) plaque, but might not be an exclusively junctional component. May have a house-keeping rule. Is involved in pre-mRNA polyadenylation. Enhances SSU72 phosphatase activity (By similarity). Found in a heat-sensitive complex at least composed of several cleavage and polyadenylation specific and cleavage stimulation factors. Interacts with CPSF2, CPSF3 and CSTF2. Interacts (via N-terminus) with HSF1; this interaction is direct and occurs upon heat shock. Interacts with SSU72. Cytoplasmic face of adhesion plaques (major) and nucleoplasm (minor) (in cells with TJ). Nucleoplasm (in cells without TJ). Nuclear bodies of heat-stressed cells. Colocalizes with HSF1 in nuclear stress bodies upon heat shock. The HEAT repeats have been determined based on 3D-structure analysis of the D.melanogaster ortholog and are not detected by sequence-based prediction programs. Belongs to the Symplekin family.