What happens when a receptor protein receives a chemical messenger?

When a receptor protein receives a chemical messenger, it initiates a series of events that ultimately changes the cell's internal environment. Receptor proteins are integral components of the cell membrane, and they are specifically designed to bind to particular signaling molecules or chemical messengers, such as hormones or neurotransmitters.

Once a chemical messenger binds to its corresponding receptor, it causes a conformational change in the receptor protein. This change activates a signal transduction pathway within the cell, which can lead to various cellular responses such as gene expression, alterations in enzyme activity, changes in ion channel permeability, or modifications in metabolic processes. These responses directly affect the state and functions of the cell, demonstrating how the cell's internal environment is modified as a result of receptor activation.

This understanding is critical in pharmacology and cell biology, as it explains how cells communicate and respond to external signals, thereby influencing their behavior and physiology.