lig om ers ▁as ▁previously ▁thought , ▁and ▁in ▁fact ▁many ▁systems ▁have ▁demonstrated ▁al lost ery ▁within ▁single ▁en zym es . ▁In ▁bio chem istry , ▁al loster ic ▁reg ulation ▁( or ▁al loster ic ▁control ) ▁is ▁the ▁reg ulation ▁of ▁a ▁protein ▁by ▁binding ▁an ▁effect or ▁mole c ule ▁at ▁a ▁site ▁other ▁than ▁the ▁en zym e ' s ▁active ▁site . ▁ ▁The ▁site ▁to ▁which ▁the ▁effect or ▁bind s ▁is ▁term ed ▁the ▁al loster ic ▁site . ▁Al loster ic ▁sites ▁allow ▁effect ors ▁to ▁bind ▁to ▁the ▁protein , ▁often ▁resulting ▁in ▁a ▁conform ational ▁change ▁involving ▁protein ▁dynamics . ▁Effect ors ▁that ▁enh ance ▁the ▁protein ' s ▁activity ▁are ▁referred ▁to ▁as ▁al loster ic ▁activ ators , ▁whereas ▁those ▁that ▁decrease ▁the ▁protein ' s ▁activity ▁are ▁called ▁al loster ic ▁in hib itors . ▁▁ ▁Al loster ic ▁reg ulations ▁are ▁a ▁natural ▁example ▁of ▁control ▁loops , ▁such ▁as ▁feedback ▁from ▁down stream ▁products ▁or ▁feed forward ▁from ▁up stream ▁substr ates . ▁Long - range ▁al lost ery ▁is ▁especially ▁important ▁in ▁cell ▁signal ing . ▁Al loster ic ▁reg ulation ▁is ▁also ▁particularly ▁important ▁in ▁the ▁cell ' s ▁ability ▁to ▁adjust ▁en zym e ▁activity . ▁ ▁The ▁term ▁al lost ery ▁comes ▁from ▁the ▁Greek ▁all os ▁( ἄ λ λ ος ), ▁" other ," ▁and ▁s tere os ▁( σ τ ε ρ ε ὀ ς ), ▁" sol id