Biological Membranes - A. N. Ogurtsov 2012

Electrogenesis of Biomembranes
Intracellular Signaling
cGMP

The second nucleotide used as an intracellular messenger is cyclic guanosine monophosphate (cGMP) (Figure 144(6)). In photoreceptor Cells in the dark, the enzyme guanylyl cyclase synthesizes cGMP from GTP.

Similarly to the Olfaction system, in dark-adapted photoreceptor cells, cGMP stimulates the corresponding channel Proteins to open sodium Ion Channels in the membrane, leading to membrane depolarization from -70 mV to -40 mV. Upon illumination, the cytosolic concentration of cGMP drops, and the Membrane Potential falls back to -70 mV. These shifts in membrane potential serve as the light intensity information transmitted to other cells.



Last update: 13/08/2026

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