הממברנה המיטוכונדריאלית הפנימית

The inner mitochondrial membrane comprises structurally and functionally distinct domains.

The inner boundary membrane is the region lying immediately adjacent to the outer mitochondrial membrane.

It contains assembly factors that organize individual complexes of the electron transport chain into a large functional supercomplex.

The composition of the inner boundary membrane is heterogenous, with localized regions of higher protein complexes such as the mitochondrial contact site and cristae organizing system or MICOS, ATP synthase, and distinct phospholipids such as cardiolipin.

Together these factors promote the invagination of the inner membrane into the matrix space, forming an in-fold known as a crista. The network of multiple cristae within the inner membrane is called the cristae membrane.

The cristae membrane and the inner boundary membrane are separated by a narrow tubular pore-like structure known as the crista junction.

The characteristic curvature of the crista junction is supported by MICOS, that prevents dynamic mixing of distinct proteins and lipids between different compartments.

As a result, each membrane compartment has a defined composition necessary for efficient mitochondrial functioning.