<prompt> Transducin is a protein found in?GlomerulusRetinaSkeletal muscleAdrenal medulla  <response>: ANSWER: B RetinaREF: Ganong 22nd edition, chapter 8, from December 2010Repeat Transducin also called Gt is a heterotrimeric G protein that is naturally expressed in vertebrate retina rods and conesMechanism of action: Heterotrimeric Transducin alpha-beta-gamma subunits is activated by a conformational change in rhodopsin due to the absorption of a photon by rhodopsins active group retinal. Activation causes the GDP bound to the alpha subunit to be exchanged with GTP from solution and results in activated alpha dissociating from beta-gamma. Active Transducin-alpha then causes cyclic GMP Phosphodiesterase to increase its activity, thereby lowering the concentration of cGMP, an intracellular second-messenger molecule. Decrease in cGMP concentration leads to the closure of cGMP-regulated Na and Ca2 ion channels and a hyperpolarized membrane potential. This chain of signaling events is also called the vertebrate photo transduction cascade 