in addition , a theoretical analysis based upon experimentally determined parameters for two in vivo cyclic cascade systems ( pyruvate kinase and glycogen phosphorylase ) revealed that under normal conditions , cyclic phosphorylation/dephosphorylation cascades consume only a small proportion ( less than 0.02 % ) of the total cellular energy flux .
C0034348
pyruvate kinase
C0031715
phosphorylation