Characterization of a REG/PA28 proteasome activator homolog in Dictyostelium discoideum indicates that the ubiquitin- and ATP-independent REGgamma proteasome is an ancient nuclear protease.

Characterization of a REG/PA28 proteasome activator homolog in Dictyostelium discoideum indicates that the ubiquitin- and ATP-independent REGgamma proteasome is an ancient nuclear protease.