Proteins comprise a group of complex organic molecules that are composed of chains of amino acids. Proteins contain the elements carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur. Proteins are fundamental components of all lifeforms.
Life was formed on Earth, in a region later known as France, when amino acids combine to form the first proteins. (TNG: "All Good Things...")
In a holosuite program of Alture VII the protein baths would carry you off on a cloud of chromal vapor into a meditation chamber. (TNG: "Birthright, Part I")