Is Adenylyl Cyclase Embedded in the Cell Membrane?

What Second Messengers Do GPCR Signals Trigger in Cells? ... One especially common target of activated G proteins is adenylyl cyclase, a membrane-associated enzyme that, when activated by the GTP-bound alpha subunit, catalyzes synthesis of the second messenger cAMP from molecules of ATP.

Is adenylyl cyclase associated with the membrane?

Adenylyl cyclases are integral membrane proteins that consist of two bundles of six transmembrane segments. Two catalytic domains extend as loops into the cytoplasm, as depicted in the figure to the right. A soluble (non-membrane bound) form of adenylyl cyclase has recently been characterized in mammalian sperm.

What binds to a receptor in the cell membrane?

Receptor sites can be found within the plasma membrane of a cell, which acts as a boundary between the cell's internal and external environment. Molecules that bind to receptor sites are known as ligands. Hormones, neurotransmitters, and drugs are examples of ligands.