Involved in oxygen transport from the lung to the various peripheral tissues. Heterotetramer of two alpha chains and two beta chains. Red blood cells. Inbred mouse strains possess 1 of 4 alleles at the HBB locus: D (diffuse), S (single), P and W1. The D and P alleles are actually closely linked doublets that coordinately express a major and a minor chain, the minor chain being slightly different in the two alleles. The S allele produces only 1 chain, it is characteristic of North American wild mice. The W1 allele is observed mainly in Northwestern China. The D-major sequence is shown. See also the entry for the beta D and P-minor chain. Belongs to the globin family.