Receptor vocabulary is the grammar of a great deal of molecular research. Once these words are clear, large parts of the literature become readable. None of the terms below describe outcomes — they describe relationships and classifications.
Core terms
Ligand
A ligand is any molecule that binds to a receptor. Binding is a physical relationship; it says nothing by itself about benefit or harm.
Agonist
An agonist is a ligand that activates a receptor when it binds. In the incretin literature — see the GLP-1 analog reference — "agonist" is a classification term.
Antagonist
An antagonist binds a receptor but blocks or dampens its activation. Agonist and antagonist are opposites in mechanism terminology.
Analog
An analog is a molecule structurally related to a reference compound. "Analog" describes structure, not equivalence of effect — an important distinction when reading about dual incretin or multi-receptor topics.
Receptor pathway
A receptor pathway is the chain of signaling events associated with a receptor. Research often studies one step of a pathway in isolation, which is why model context matters so much.
Reading terms in context
When a study says a molecule is a "selective agonist" at a particular receptor, it is making a precise, narrow claim about binding and activation in a specific system. It is not claiming a real-world result. Pair this glossary with Why Study Context Matters to read accurately.