Question

How do peptide hormones induce a signaling cascade?

A) By binding to intracellular receptors.
B) By directly entering the nucleus and altering gene expression.
C) By binding to cell surface receptors and activating intracellular signaling pathways.
D) By inhibiting enzyme activity in the cytoplasm.

Answer 1

Peptide hormones induce a signaling cascade by binding to cell surface receptors and activating intracellular signaling pathways.

Step-by-step explanation:

Because amino acid-derived hormones and polypeptide hormones are not lipid-soluble, they bind to plasma membrane hormone receptors located on the outer surface of the membrane. Unlike steroid hormones, they cannot act directly on DNA but activate a signaling pathway; this triggers intracellular activity and carries out the specific effects associated with the hormone. The hormone that initiated the signaling pathway is called a first messenger. In the case of the epinephrine signaling pathway, binding of the amino acid-derived hormone epinephrine to its receptor activates a G-protein which, in turn, activates cAMP, a second messenger, ultimately resulting in a cellular response such as the conversion of glycogen to glucose.