Agonist vs. Protagonist — What's the Difference?

An agonist is a chemical that binds to a receptor and activates the receptor to produce a biological response. In contrast, an antagonist blocks the action of the agonist, while an inverse agonist causes an action opposite to that of the agonist.

A protagonist (from Ancient Greek πρωταγωνιστής, prōtagōnistḗs 'one who plays the first part, chief actor') is the main character of a story. The protagonist makes key decisions that affect the plot, primarily influencing the story and propelling it forward and is often the character who faces the most significant obstacles.

(Physiology) A contracting muscle that is resisted or counteracted by another muscle, the antagonist.

The main character in a work of fiction, as a play, film, or novel.

A substance that can combine with a receptor on a cell to initiate signal transduction.

In ancient Greek drama, the first actor to engage in dialogue with the chorus, in later dramas playing the main character and some minor characters as well.

One involved in a struggle or competition.

A leading or principal figure.

Someone involved in a contest or battle (as in an agon), protagonist.

The leader of a cause; a champion.

The muscle that contracts while the other relaxes.

Usage Problem A proponent; an advocate.

A molecule that can combine with a receptor on a cell to produce a physiological reaction.

(authorship) The main character, or one of the main characters, in any story, such as a literary work or drama.

One who contends for the prize in public games.

A leading person in a contest; a principal performer.

The principal character in a work of fiction

(proscribed) An advocate or champion of a cause or course of action.

Someone involved in a contest or battle (as in an agon)

One who takes the leading part in a drama; hence, one who takes lead in some great scene, enterprise, conflict, or the like.

A muscle that contracts while another relaxes;

A person who backs a politician or a team etc.;

(biochemistry) a drug that can combine with a receptor on a cell to produce a physiological reaction

The principal character in a work of fiction