MSH: The oxygen-carrying proteins of ERYTHROCYTES. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements.,CSP: oxygen carrying pigment of the erythrocytes; a complex protein composed of four heme groups and four globin polypeptide chains.,NCI: The substance inside red blood cells that binds to oxygen in the lungs and carries it to the tissues.,NCI: The red respiratory protein of erythrocytes, consisting of approximately 3.8% heme and 96.2% globin (64.5 KD), which as oxyhemoglobin (HbO2) transports oxygen from the lungs to the tissues where the oxygen is readily released and HbO2 becomes Hb.