Question

Describe the “Intracellular Receptor Model” and describe completely a specific example of how this model works.

Answer 1

Signaling a cell can happen with the help of two receptors:-

i) Extracellular receptor:- These receptors are present outside or on the outer membrane of the cell.

ii) Intracellular receptor:- These receptors are present inside the cell typically in the cytoplasm or nucleus. Ligands of these receptors are small and hydrophobic as they have to pass through the lipid bilayer of the cell membrane in order to reach their receptors.

For example:- hydrophobic steroid hormones such as sex hormones like estradiol and testosterone are intracellular.

When a hormone enters a cell and binds to its receptor, it causes the receptor to change shape, allowing the receptor-hormone complex to enter the nucleus and regulate gene activity. Hormone binding exposes regions of the receptor that have DNA-binding activity, meaning they can attach to specific sequences of DNA. These sequences are found next to certain genes in the DNA of the cell, and when the receptor binds next to these genes, it alters their level of transcription.