OperoncontrolmodelnegativepositiveInd.activeinactiveRep.inactiveactive
Operon control model negative positive Ind. Rep. inactive active active inactive
.Negative-inducible operon（多为分解酶类，Lacoperon---调控机理I→activerepressorX38kd/monomertetramer152kd与 特异结合operatoroperon off
I active repressor I 38 kd / monomer tetramer 152 kd • Negative—inducible operon (多为分解酶类，Lac operon) -调控机理 与 operator 特异结合 operon off
Inducer（lactose）与repressor特异结合tetramer变构特异结合力cut down on 1000Xoperon on作用于0位点上的repressor→变构→脱离o位作用于游离的repressor→变构→失去结合于0位的能力
I Inducer (lactose) 与 repressor 特异结合 tetramer 变构 特异结合力 cut down on 1000× operon on 作用于O 位点上的 repressor 变构 脱离O位 作用于游离的 repressor 变构 失去结合于O位的能力
Lactose is inducer of Lac operon40Rep. +lacO32p-IPTGNo IPTGRep.+Laco30unn%20Rep.+IPTGwhichpreventsRep+Laco10+IPTG金公0.10.20.30.4IPTG;异丙基-β-D-硫代半乳Repressor(ug/mL)糖苷，自己不被分解的安殿诱导物（lactoseanalog）Cohn.Journal of MolecularBiology.Vol34:366.1968
Rep.＋lacO32p Cohn. Journal of Molecular Biology, Vol. 34: 366. 1968 Lactose is inducer of Lac operon IPTG;异丙基-β-D-硫代半乳 糖苷，自己不被分解的安慰 诱导物（lactose analog） No IPTG Rep.＋LacO Rep.＋IPTG which prevents Rep＋LacO
mRNAstartpointGOObstruction?Competition?unwinding405020201101030RNApolymerasebindingRepressor bindingOgene(operator)cis-actionfactor
RNA polymerase binding mRNA start point Obstruction? Competition? Repressor binding O gene (operator) cis-action factor unwinding