This is an example of competetive binding. IkB binds to active form of NFkB to form a complex. IKK phosphorylates IkB, and the phosphorylated IkB is ubiquinated automatically, and degraded. The phosphorylated form of IkB can not bind to NFkB. Therefore, IkB is an inhibitor of NFkB, while IKK decreases the amount of unphosphorylated IkB, thus prevent it from binding NFkB. 0.0 s5 PROTEIN p44 s5 PROTEIN p43 inactive active inactive inactive inactive active inactive inactive inactive inside PROTEIN p42 inside COMPLEX Complex_br_(I_kappa_B/NF_kappa_B) inside PROTEIN p44 inside DEGRADED a127_degraded inside PROTEIN p43 inside PROTEIN p43 inside PROTEIN p43 STATE_TRANSITION 0.3333333333333339,0.0 0.666666666666667,-8.881784197001252E-16 sa3 sa2 sa1 HETERODIMER_ASSOCIATION 0.37535319738994755,0.3119209854949414 sa3 sa5 csa1 STATE_TRANSITION 0.3333333333333339,0.0 0.666666666666667,-1.7763568394002505E-15 sa2 sa4 STATE_TRANSITION 0.3333333333333339,0.0 0.6666666666666679,0.0 sa4 sa6