Hemoglobin

Hemoglobin is an iron-containing protein in red blood cells that transports oxygen from respiratory organs to body tissues, where oxygen supports aerobic respiration. It is a metalloprotein, chromoprotein, and globulin. Mammalian hemoglobin can bind up to four oxygen molecules and also carries some carbon dioxide and nitric oxide. Hemoglobin-like molecules occur in many invertebrates, fungi, and plants, where they can carry or regulate small molecules and ions.

Primary function

Transports oxygen in red blood cells

Mammalian oxygen binding

Up to four oxygen molecules per molecule

Other gas transport

Carries some carbon dioxide and nitric oxide