The 2.4 Å structure of the Ca2+-bound calpain 2 heterodimer bound to one of the four inhibitory domains of calpastatin. Calpastatin seems to inhibit calpain by occupying both the primed and unprimed sides of the active site cleft. This crystal structure also reveals the conformational changes that calpain undergoes upon binding calcium, which include opening of the active site cleft and movement of the domains relative to each other to produce a more compact enzyme.
- Rachel A. Hanna
- Robert L. Campbell
- Peter L. Davies