Question

Describe how the enzyme adenylyl cyclase is activated by the binding of epinephrine to its receptor.

Answer 1

Ans) epinephrine receptors are GPCR (Gprotein coupled receptor).

Gpcr typically have 7 membrane spanning domain. In the absence of signal molecule that is epinephrine the heteromeric G protein complex is in inactive GDP bound form. On binding off hormone epinephrine to the the receptor there is conformational change of the receptor and activation of G protein complex. This results from the exchange of GDP with GTP on the alpha subunit after which Alpha (α)and beta gamma(β¥) dissociate. The α subunit binds to effector enzyme that is adenyl cyclase. This binding of alpha subunit to adenyl cyclase cause its activation and generates secondary messanger ie cAMP. Cyclic AMP directly activates cAMP dependent protein kinaseA whitch catalyse the phosphorylation of other protein kinase and phosphorylation of structural gene for transcription.