BAG3

BAG family molecular chaperone regulator 3 is a protein that in humans is encoded by the BAG3 gene. BAG3 is involved in chaperone-assisted selective autophagy (CASA).

BAG gene has been implicated in age related neurodegenerative diseases such as Alzheimer's. It has been demonstrated that BAG1 and BAG 3 regulate the proteasomal and lysosomal protein elimination pathways, respectively. It has also been shown to be the cause of familial dilated cardiomyopathy. That BAG3 mutations are responsible for familial dilated cardiomyopathy is confirmed by another study describing 6 new molecular variants (2 missense and 4 premature Stops ). Moreover, the same publication reported that BAG3 polymorphisms are also associated with sporadic forms of the disease together with HSPB7 locus.

In muscle cells, BAG3 cooperates with the molecular chaperones Hsc70 and HspB8 to induce the degradation of mechanically damaged cytoskeleton components in lysosomes. This process is called chaperone-assisted selective autophagy (CASA) and is essential for maintaining muscle activity in flies, mice and men.

BAG3 is able to stimulate the expression of cytoskeleton proteins in response to mechanical tension by activating the transcription regulators YAP1 and WWTR1. BAG3 balances protein synthesis and protein degradation under mechanical stress.

Interactions
BAG3 has been shown to interact with HSPA8, HSPA1A, PLCG1, Dynein, SYNPO2, LATS1, and AMOTL1