SANS investigation of assembly state of proteasome activator 28 and the 20S proteasome

Abstract

The state of proteasome activator 28 (PA28) and the formation of the proteasomal complex in an aqueous solution are investigated with small-angle neutron scattering (SANS). The most appropriate state of PA28, which well reproduces the observed SANS profile, is the dissociation equilibrium between dimer and monomer with dissociation degree of 0.5. In addition, it is revealed that the packing of PA28 in the dimer is same as that in a crystal. It is also revealed that the proteasomal complex in which two PA28s connects to both basal planes of the 20S proteasome is spontaneously formed in the mixture solution of PA28 and the 20S proteasome. © 2010 IOP Publishing Ltd.