Write the characteristic features of the peptide hormones?

Explanation

Peptide phospolipid cell membrane and bind to the receptors on the exterior cell surface. They are are transported to the golgi, which is the site of modification. It acts as a first messenger in the cell. Hormones on binding to their receptors do not enter the target cell but generate the production of second messengers such as cyclic AMP (c AMP), which in tum regulates cellular metabolism. This is catalyzed by the enzyme adenylate cyclase. The interaction between the hormone at the surface and the effect brought out by cAMP within the cell is known as signaling cascade. At each step there is a possibility of amplification. (i) One hormone molecule may bind to multiple receptor molecule before it is degraded.
(ii) Each receptor may activate several adenylate cyclases each of which make much c AMP.
(iii) Thus there is more signal after each step.
The actions of cAMP are terminated by phosphodiesterases. The effect of peptide hormones like insulin, glucagon, somatotropin are usually. short lived because they work through second messenger system.