Involved in oxygen transport from the lung to the various peripheral tissues. Hemopressin acts as an antagonist peptide of the cannabinoid receptor CNR1. Hemopressin-binding efficiently blocks cannabinoid receptor CNR1 and subsequent signaling. Heterotetramer of two alpha chains and two beta chains. Red blood cells. Horse has two non-allelic alpha chains, slow and fast. The slow chain sequence is shown. Belongs to the globin family. The man behind the molecular lung - Issue 21 of April 2002