protein - any of a large group of nitrogenous organic compounds that are essential constituents of living cells; consist of polymers of amino acids; essential in the diet of animals for growth and for repair of tissues; can be obtained from meat and eggs and milk and legumes; "a diet high in protein"

actin - one of the proteins into which actomyosin can be split; can exist in either a globular or a fibrous form

albumen, albumin - a simple water-soluble protein found in many animal tissues and liquids

globulin - a family of proteins found in blood and milk and muscle and in plant seed

globin, haematohiston, hematohiston - a colorless protein obtained by removing heme from hemoglobin; the oxygen carrying compound in red blood cells

glutelin - a simple protein found in the seeds of cereals

histone - a simple protein containing mainly basic amino acids; present in cell nuclei in association with nucleic acids

prolamine - a simple protein found in plants

protamine - a simple protein found in fish sperm; rich in arginine; simpler in composition than globulin or albumin; counteracts the anticoagulant effect of heparin

albuminoid, scleroprotein - a simple protein found in horny and cartilaginous tissues and in the lens of the eye