Sarcomere

Within each skeletal muscle cell are many myofibrils consisting of a repeating array of a specialized structure

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Crista junction

The connection between the inner boundary membrane and a crista

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The curvature of the crista junctions is due to a protein complex called MICOS (mitochondrial contact site and cristae organizing system).

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MICOS has an integral membrane protein subunit that homo-oligomerizes and bends the inner membrane to produce high curvature.

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MICOS mediates close juxtaposition of the outer membrane and inner membrane by binding to outer membrane–associated proteins

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The binding partners for MICOS in the outer membrane are Tom and SAM protein complexes, (involved in import of proteins into the mitochondria). 

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MICOS function as a diffusion barrier to prevent mixing of the distinct proteins and lipids in the boundary membrane and crista membranes.