For the investigation at the X-ray laser, the researchers grew tiny crystals of the serotonin receptor with the molecule ergotamine attached, which is a migraine drug that targets this receptor. (sciencedaily.com)
That idea was reinforced in the late 1930s with the publication of a paper on the use of ergotamine tartrate, an alkaloid that was known to constrict blood vessels. (scientificamerican.com)