|Phosphorylation sites||Stress inducibility||Metal ion interaction||α-Synuclein formation||Amyloid aggregation and cytotoxicity||Metal ion-induced aggregation of amyloid and α-synuclein and oxidative stress||Functions|
Human—MK2-, MK3-, and MK5-mediated phosphorylation at S15, S78, and S82 residues.|
Chinese hamster—S15, S90 residues.
Murine Hsp25 (HSPB1)—phosphorylation by protein kinase C and cAMP-dependent kinase at S15 and S86 residues.
|Positive||Expression is induced by Cu2+and also by Cd2+.||Prevent||Inhibit aggregation but does not have a role in preventing cytotoxicity||Protective role in Cu2+- induced aggregation and oxidative stress||Modulates p53 pathway by inhibiting cellular senescence and also prevents apoptosis by interfering both caspase-dependent and caspase-independent pathways. It also possesses chaperone activity and also prevents the cell death pathway triggered by a rise in levels of ROS.|
|Hsp20 (HSPB6)||Protein kinase A (PKA)/protein kinase G (PKG) phosphorylation at S16 residue.||Negative||–||Prevent||Prevent aggregation and attenuate cytotoxicity||–||Phosphorylation at S16 residue leads to antiapoptotic function where it inhibits mitochondria-mediated apoptosis . It also possesses chaperone activity.|
α-A crystallin (HSPB4)—cAMP-dependent kinase-mediated phosphorylation at S122 and 3 other phosphorylation sites between 122 and 178 residues.|
α-B crystallin (HSPB5)—phosphorylation at S19 residue which is age-dependent, S45 residue during mitosis and in heat stress conditions at S59 residue.
α-A crystallin expression is induced by Cu2+ and Zn2+.|
α-B crystallin expression is induced by Cu2+ and also by Cd2+ and Zn2+.
|Prevent||Inhibit aggregation and prevent cytotoxicity||Protective role in Cu2+-induced aggregation and oxidative stress||Prevent TNFα-mediated apoptosis, mitochondria-mediated apoptosis, and cytochrome c interaction in apoptosis. It also modulates P53 pathway involving senescence and chaperone activity.|
|Hsp22 (HSPB8)||cAMP-dependent protein kinase phosphorylation at S24 and S57 residues.||Positive based on cell type||–||Prevent and are more potent in nature||Inhibit aggregation and cytotoxicity||–||Major function is chaperone activity. It is actively involved in macroautophagy.|