CSL-dependent transcription assays in OT11 allow determination of minimal requirements for ternary complex formation.
A). In the absence of CSL, neither full-length NICD nor fragments of NICD can activate transcription. B). In the presence of CSL, only RAMANKNLS and NICD result in transcriptional activation. C). Fusion of CSL-ANKNLS (CAN) activates transcription 6-fold over empty vector alone (and relative to CSL and ANKNLS), consistent with an increased effective concentration of ANK at the CTD of CSL. Co-transfection of RAM with CAN further increases transcriptional activation, implicating an additional role of RAM in forming the active ternary complex.