What does the mitochondrial protein porin do?

Mitochondrial porins, or voltage-dependent anion-selective channels (VDAC) allow the passage of small molecules across the mitochondrial outer membrane, and are involved in complex interactions regulating organellar and cellular metabolism.

What is porin structure?

OM porins are transmembrane pore-forming proteins with a β-barrel structure, which forms a water-filled open channel and allows the passive transport of hydrophilic compounds (Schulz, 2002; Nikaido, 2003; Pages et al., 2008).

What is the Intermembrane of the mitochondria?

The intermembrane space (IMS) of mitochondria is enclosed by the outer and the inner membrane of the organelle. The IMS can be subdivided into two distinct subcompartments, the intracristae space and the lumen between the outer and the inner membrane, which is also called the “external IMS”.

How proteins are transported to mitochondria?

Proteins are translocated into the mitochondrial matrix space by passing through the TOM and TIM complexes at sites of adhesion between the outer and inner membranes known as contact sites. A second set of hsp70 proteins in the matrix or stroma bind to the incoming polypeptide chain to pull it into the organelle.

How are proteins imported into the mitochondrial matrix?

Mitochondrial Precursor Proteins Are Imported into the Matrix at Contact Sites That Join the Inner and Outer Membranes. In principle, a protein could reach the mitochondrial matrix by crossing the two membranes one at a time, or it could pass through both at once.

Where are protein translocators located in the mitochondria?

Three protein translocators in the mitochondrial membranes. The TOM and TIM complexes and the OXA complex are multimeric membrane protein assemblies that catalyze protein transport across mitochondrial membranes. The protein components of the TIM22 and (more…) Mitochondrial Precursor Proteins Are Imported as Unfolded Polypeptide Chains

How are proteins transported into the intermembrane space?

It initially transports their signal sequences into the intermembrane space and helps to insert transmembrane proteins into the outer membrane. The TIM23 complex then transports some of these proteins into the matrix space, while helping to insert transmembrane proteins into the inner membrane.

Where is cytochrome oxidase located in the mitochondrial membrane?

A signal sequence for mitochondrial protein import. Cytochrome oxidase is a large multiprotein complex located in the inner mitochondrial membrane, where it functions as the terminal enzyme in the electron-transport chain (discussed in Chapter 14). (A) (more…)