The rhomboid-like superfamily: molecular mechanisms and biological roles

The rhomboid proteases were first discovered as regulators of Drosophila EGF receptor signaling; soon after, it was recognized that they represented the founder members of a widespread family of intramembrane serine proteases conserved in all kingdoms. More recently still, the family was promoted to a superfamily, encompassing a wide variety of distantly related proteins. One of the surprises has been that many members of the rhomboid-like superfamily are not active proteases. Given the size of this clan, and its relatively recent discovery, there is still much to learn. Nevertheless, we already understand much about how rhomboid proteases perform their surprising function of cleaving transmembrane domains. We also already know that members of the rhomboid-like superfamily participate in biological functions as diverse as growth factor signaling, mitochondrial dynamics, inflammation, parasite invasion, and the machinery of protein quality control. Their potential medical significance is now becoming apparent in several areas.