Question

Why does signaling through a peptide growth factor (such as Epidermal Growth Factor) allow for more rapid responses in a cell than signaling through a steroid hormone such as estrogen?

Answer 1

Signaling through a peptide growth factor (such as Epidermal Growth Factor) allow for more rapid responses in a cell than signaling through a steroid hormone such as estrogen because EGF is a growth factor that play a critical role in controlling animal proliferation . It allows rapid responses because these are unable to cross the plasma membrane of their target cells , so they act by binding to cell surface receptors. They bind to receptors present on the cell surface directly and their effect is that this allows more rapid responses in a cell. Steroid hormones such as estrogen are having hydrophobic character and they are able to enter cells by diffusing across the plasma membrane. Once they get inside the cell, they bind to intracellular receptors and this binding expresses effect on responsive target cells. Hence there response is slower than that of peptide growth factors.

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