Gap junctions permit the passage of molecules as large as 1.2 nm in diameter (molecules smaller than 1200 Da).

TLS Online TPP Program

#Id: 7911

#XL - Q Biochemistry

MCSs also serve as interfaces for the transfer of ions (Ca+2 ) and small molecules (glycerophospholipids) between the ER and mitochondria.

TLS Online TPP Program

#Id: 7910

#XL - Q Biochemistry

Mitochondria-associated membranes (MAMs)

The portions of the ER membranes that form special contact regions with the mitochondria.

TLS Online TPP Program

#Id: 7909

#XL - Q Biochemistry

Membrane contact sites (MCSs)

Mitochondria establish MCSs with many other organelles, including ER, lysosomes, peroxisomes, the plasma membrane, the Golgi, endosomes, and even lipid droplets.

TLS Online TPP Program

#Id: 7908

#XL - Q Biochemistry

In healthy mitochondria, PINK1 resides in the mitochondrial matrix.

In damaged or dysfunctional mitochondria, PINK1 resides on the outer mitochondrial membrane, where it recruits cytosolic Parkin.

TLS Online TPP Program

#Id: 7907

#XL - Q Biochemistry

Parkinson’s disease is caused by mutations in two gene encoding proteins that can mediate mitophagy:

PINK1 (a kinase)

Parkin (E3 ubiquitin ligase)

TLS Online TPP Program

#Id: 7906

#XL - Q Biochemistry

When the environment of a cell has inadequate oxygen, enzymatic modification of proteins on the outer mitochondrial membrane induces mitophagy.