An enzyme-linked receptor, also known as a catalytic receptor, is a transmembrane receptor, where the binding of an extracellular ligand causes enzymatic activity on the intracellular side.^[1] Hence a catalytic receptor is an integral membrane protein possessing both catalytic, and receptor functions.^[2]

They have two important domains, an extra-cellular ligand binding domain and an intracellular domain, which has a catalytic function; and a single transmembrane helix. The signaling molecule binds to the receptor on the outside of the cell and causes a conformational change on the catalytic function located on the receptor inside the cell.

Examples of the enzymatic activity include:

• Receptor tyrosine kinase, as in fibroblast growth factor receptor. Most enzyme-linked receptors are of this type.^[3]
• Serine/threonine-specific protein kinase, as in bone morphogenetic protein
• Guanylate cyclase, as in atrial natriuretic factor receptor

The following is a list of the five major families of catalytic receptors: