Muscle cells have an abundant, modified smooth ER called the sarcoplasmic reticulum.

The release and reuptake of Ca2+ by the sarcoplasmic reticulum trigger myofibril contraction and relaxation, respectively

TLS Online TPP Program

#Id: 7904

#XL - Q Biochemistry

TLS Online TPP Program

#Id: 7905

#XL - Q Biochemistry

Mitophagy provides Mitochondrial Quality Control

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.

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: 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: 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.