Two isomers of cytochrome b5, referred to as the A (major) and B (minor) forms, differ by a 180° rotation of the heme about an axis defined by the α- and γ-meso carbons.
Hai dous isómeros do citocromo b5, denominados formas A (maior) e B (menor), que difiren por unha rotación de 180° do hemo arredor dun eixe definido polos carbonos α- e γ-meso.