Answer:
The signal transduction may be defined the phenomena of the transfer of signal by the different cascade mechanisms that occur in the cell by the subsequent phosphorylation and dephosphorylation.
The Sutherland has worked on the glycogen metabolism and has indicated that these signaling molecules do not have the direct ability to interact with the enzymes present in the cytosol. They require the molecule that can intact the plasma membrane and thus activates the enzyme for phosphorylation.
