The enzymatically active substrate (ribulose 1,5-bisphosphate) binding sites are located in the large chains that form dimers as shown in Figure 1 (above, right) in which amino acids from each large chain contribute to the binding sites.
De enzymaktive substrat (ribulose-1,5-bisfosfat)-bindingssteder findes i de lange kæder, der danner dimere forbindelser, som vist på figur 1 (ovenfor til højre), hvor aminosyrer fra hver af de lange kæder bidrager til bindingsstederne.