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 conjugated protein having a carbohydrate component

a conjugated protein linked to a compound of iron and porphyrin

a conjugated protein having a lipid component; the principal means for transporting lipids in the blood