FIG. 7.

Differential use of domains by CoCoA with β-catenin and GRIP1. (A) When CoCoA serves as a secondary coactivator for β-catenin, the N-terminal and C-terminal regions of CoCoA (N and C in the diagram) bind to β-catenin and serve as signal input domains. The N-terminal domain may also serve as a signal output domain to transmit the activating signal (thick arrow) to an unknown target (possibly p300/CBP which bind to this domain) in the transcription machinery, but the C-terminal domain is dispensable. Other coactivators, such as GRIP1, CARM1, and p300/CBP, can also participate in this complex. (B) When CoCoA serves as a secondary coactivator for GRIP1, the coiled-coil domain of CoCoA binds to GRIP1 and serves as signal input domain. The C-terminal activation domain serves as a signal output domain, transmitting the signal to an unknown downstream target. Other coactivators, such as CARM1 and p300/CBP, can also participate in this complex. RE, response element or enhancer element; TF, DNA-binding transcription factor; C-C, coiled-coil domain; pol II complex, RNA polymerase II plus basal transcription factors; TATA, TATA box in the basal promoter; arrow emanating from the pol II complex, transcription start site and direction.