SPFH protein cage - one ring to rule them all

Stomatin/prohibitin/flotillin/HflKC (SPFH) proteins comprise a universally conserved family of membrane-associated scaffolds that compartmentalize membranes, but the detailed molecular mechanism has remained unclear. In a recent paper published in Cell Research, Ma et al. determined the cryo-EM structure of the bacterial SPFH heterodimer HflK/C, which assembles into a giant molecular cage encasing four AAA+ protease hexamers; the structural work elucidates how SPFH proteins confine their client proteins in specialized membrane microdomains.