Filament structures in the intracristal compartment of rat liver mitochondria after permeability transition

Here we describe filament-shaped structures in isolated rat liver mitochondria that have undergone permeability transition. The filaments are found exclusively in the intracristal part of the intermembrane compartment, and have a diameter of 16 nm, a pitch of 14 nm and a length of about 200 nm. The filaments appear to function as connecting bridges between different parts of the inner membrane. Similar filaments have previously been described in mitochondria of several different cell types and tissues. These findings suggest the existence of an, as yet, unidentified protein complex in the mitochondrial intermembrane compartment.