Chaperone: 1. Any protein that is required for the proper folding or assembly of another protein or protein complex without being a component of the final structure. 2. A woman who is present when a male physician examines a female patient. 3. Anyone present when a physician examines a patient of the opposite sex from the physician.
From the original meaning of chaperone as a person (usually a matron) who accompanied an unmarried woman in public or mixed company for the sake of propriety.