What are Chaperones?

About Chaperones:

• Chaperones are a group of proteins that have functional similarity and assist in protein folding.
• They are proteins that can prevent non-specific aggregation by binding to non-native proteins.
• After the new protein chain has been shaped correctly, chaperones move on. Or else the new chain is eliminated.
• Without chaperones, newly synthesised proteins would soon become a tangled mess of insoluble aggregates, hindering cellular processes.
• Chaperones are needed under physiological conditions too, for normal cellular function.
• There are several families of chaperones and each possesses different functions. Example of chaperon proteins are the “heat shock proteins” (Hsps).
• Major chaperones in humans include HSP70, HSC70 and HSP90: the numbers express the size of the proteins in kilodaltons.
  • In normal cells 1%–2% of all proteins present are heat shock proteins. This number rises threefold during stressful conditions.
• Misfolding of proteins can cause a number of diseases namely:
  • Parkinson's disease: In which Alpha-synuclein protein, present in neurons, is wrongly folded.
  • Alzheimer: Brains of Alzheimer's patients have plaques formed from aggregates of amyloid beta-peptide. This accumulation of amyloid fibrils is toxic, leading to widespread destruction of neurons – a 'neurodegenerative’ disorder.
  • Autosomal dominant congenital cataract: In the eye lens, an abundant subset of proteins called alpha-crystallins themselves serve as chaperones – a single R116G mutation in human alpha crystallin is responsible for this.