Proteins can play a wide array of roles in a cell or organism, such as non-enzymatic functions like binding.

One unique characteristic of proteins is their ability to bind to various biomolecules. This binding depends on the affinity and the specificity of the protein molecules. The affinity determines how readily a molecule binds to the protein while specificity determines which molecule will bind to the protein.

An example of binding is seen in the membrane transport proteins that are present in the cell membrane. When a molecule comes towards the cell, it binds to the membrane transport protein in the membrane. The molecule is then transported inside the cell when this transport protein transfers it into the cell.  The change in the protein’s conformation alters its affinity and specificity, thus controlling the voltage-gated ion channels in the cell membrane and allowing movement in and out of the cell.

Key Points

• Proteins can bind certain molecules based on their affinity and specificity.

• The affinity determines how readily a molecule binds to the protein while specificity determines which molecule will bind to the protein.

Key Terms

affinity: pertains to the attraction or compatibility between particles, elements, structures, or things

specificity: the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species

proteins: a macromolecule formed by chains of amino acids.