Phototransduction uses a signal transduction cascade similar to mechanisms stimu
ID: 816870 • Letter: P
Question
Phototransduction uses a signal transduction cascade similar to mechanisms stimulated by hormones and neurotransmitters. However, the visual sensory apparatus is stimulated by photons, and converts light energy into a nerve impulse. Determine whether each of the the following events increases phototransduction or does not increase phototransduction (either by not initiating a signal or by terminating the signal). The abbreviation cGMP is used for guanosine 3',5'-cyclic monophosphate (cyclic GMP), and PDE is used for phosphodiesterase.
Explanation / Answer
cGMP most likely mechanism of action is activation of intracellular protein kinases in response to the binding of membrane -impermeable peptide hormones to the external cell surface. So, cGMP increases in phototransduction.
Where as PDE regulate the localization, duration, and amplitude of cyclic nucleotide signaling within subcellular domains. So, PDE decreases in phototransduction.