There are two de novo methyltransferases (Dnmt3A and Dnmt3B) in the mouse; they have different target sites, and both are essential for development.

TLS Online TPP Program

#Id: 7906

#Unit 2. Cellular Organization

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

TLS Online TPP Program

#Id: 7907

#Unit 2. Cellular Organization

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: 7908

#Unit 2. Cellular Organization

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: 7909

#Unit 2. Cellular Organization

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: 7910

#Unit 2. Cellular Organization

Mitochondria-associated membranes (MAMs)

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

TLS Online TPP Program

#Id: 7911

#Unit 2. Cellular Organization

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