Transcriptional activator GLI3 (GLI3)

Has a double function as a transcriptional activator and a repressor of the sonic hedgehog (Shh) pathway, and plays a role in limb development. The full size GLI3 form (GLI3FL) after phosphorylation and nuclear translocation, functions as an activator (GLI3A) while GLI3R, its C-terminally truncated form, acts as a repressor.

A proper balance between the GLI3 activator and the repressor GLI3R, rather than the repressor gradient itself or the activator/repressor ratio gradient, specifies limb digit number and identity. In concert with TRPS1, plays a role in regulating the size of this zone of distal chondrocytes, in restricting the zone of PTHLH expression in distal cells and in activating chondrocyte proliferation.