ABSTRACT

T he best characterized endogenous activators of the 20S proteasome are the PA700 or 19S regulator and the PA28 or 1 IS regulator (1 IS REG). The 19S regulator forms the 26S proteasome by associating with the 20S proteasome in an ATP-dependent reaction which is described in detail in chapters by Glickmann et al and Gorbea and Rechsteiner. In this review we focus on structural and functional aspects of the PA28/1 IS regulator.