1) Heat shock protein 
The heat shock proteins hslV and hslU (also known as clpQ and clpY respectively) are expressed in many bacteria such as E. coli in response to cell stress. The hslV protein is a protease and the hslU protein is an ATPase; the two form a symmetric assembly of four stacked rings, consisting of an hslV dodecamer bound to an hslU hexamer, with a centr...