 Following the CP-RP association, the confirmation of certain alpha subunits will change and consequently cause the opening of substrate entrance gate.Besides RPs, the 20S proteasomes can also be effectively activated by other mild chemical treatments, such as exposure to low levels of sodium dodecylsulfate (SDS) or NP-14.The 20S proteasome subunit beta-2i (systematic nomenclature) is originally expressed as a precursor with 273 amino acids.