What is the Origin of Receptor Affinity?

The term "receptor" stems from the Latin recipere, meaning to receive, while "affinity" comes from the Latin affinitas, meaning relationship or connection. The concept of specific binding sites for hormones was proposed in the early 20th century, but the rigorous, quantitative measurement of receptor affinity using dissociation constants (Kd) was developed in the mid-to-late 20th century. This biochemical metric is now a cornerstone of pharmacology and hormonal science.

What is the Mechanism of Receptor Affinity?

The mechanism of affinity is governed by the non-covalent intermolecular forces, such as hydrogen bonds, electrostatic interactions, and hydrophobic effects, that stabilize the ligand-receptor complex. These forces must be sufficiently strong to overcome the natural tendency for the complex to dissociate. Changes in receptor structure, often due to genetic polymorphisms or post-translational modifications like phosphorylation, can alter the binding pocket's shape, thereby increasing or decreasing the receptor's affinity for its cognate hormone and profoundly impacting cellular signaling and response.

Receptor Affinity ∞ Area

Receptor Affinity

Meaning

Receptor Affinity is a quantitative measure of the strength of the binding interaction between a hormone, neurotransmitter, or drug (the ligand) and its specific cellular receptor. This intrinsic property reflects how readily the ligand associates with and remains bound to the receptor site. High receptor affinity indicates that a low concentration of the ligand is sufficient to occupy the receptor, thereby eliciting a maximal biological response. This concept is fundamental to endocrinology, as it determines the potency and effectiveness of circulating hormones on their target tissues.