What happens to the conformation of the receptor when a first messenger binds?

When a first messenger binds to its receptor, the conformation of the receptor changes. This conformational change is essential for the activation of the receptor and subsequent intracellular signaling.

Receptors are typically proteins that can exist in different shapes, or conformations, enabling them to either be active or inactive. The binding of a first messenger, which is often a hormone or neurotransmitter, induces a structural alteration in the receptor. This altered shape allows the receptor to interact with and activate different intracellular signaling proteins or second messengers, thereby transmitting the signal inside the cell and initiating a physiological response.

This process is fundamental in physiological pathways, such as hormone action, neurotransmission, and immune responses, where the change in the receptor’s conformation is critical for eliciting the desired cellular effects.