Thank you for reporting, we will resolve it shortly
Q.
In the mechanism of action of a protein hormone, one of the second messengers is
Chemical Coordination and Integration
Solution:
The molecules of hormones that are amino acid derivatives, peptides or proteins are large and insoluble in lipids and cannot enter the target cell. Therefore, they act at the cell surface. They bind to specific receptor molecules located on the surface of the cell membrane and generate second messengers, e.g., cyclic $AMP$, $IP_3$, $Ca^{++}$, etc.