The C2 cytosolic loop of adenylyl cyclase interacts with the activated form of Gαs

AbstractUsing the yeast two-hybrid system, we studied the physical interaction between the complete C1 and C2 cytosolic domains of Xenopus laevis type 9 (xl9C1, xl9C2) and the C2 domain of rat type 6 (r6C2) adenylyl cyclase (AC). Heterodimerization between xl9C1 and xl9C2 and homodimerization between C2 (but not C1) domains was observed. Interaction between C2 and human Gαs (hGαs) was also detected and was dependent on Gαs activation. In contrast X. laevis Gαs (xlGαs), which is 92% identical to hGαs, was unable to interact with any of the three AC cytosolic domains tested, corroborating previous findings that showed no effector activation. Through the construction of chimeras, we demonstrated that the amino-terminal half of xlGαs was responsible for the lack of interaction with AC. Chimeras between mouse Gαi2 and Gαs (N-mGαi2/C-Gαs), that have previously shown to activate AC to a higher extent than wild-type Gαs, also interacted with the C2 cytosolic domain and with a higher affinity. Interestingly, N-mGαi2/C-xlGαs chimera was not only able to interact with C2 but also with the C1 cytosolic domain