alpha-crystallin A2 chain (CRYAA2)

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Function

contributes to the transparency & refractive index of the lens
has chaperone-like activity, preventing aggregation of various proteins under a wide range of stress conditions
deamidation of Asn-101 in lens occurs mostly during the first 30 years of age, followed by a small additional amount of deamidation (~5%) during the next ~38 years, resulting ina maximum of ~50% deamidation during a lifetime
phosphorylation on Ser-122 seems to be developmentally regulated
- absent in the first months of life, appears during the first 12 years of life
- relative amount of phosphorylated versus unphosphorylated form does not change over a lifetime
acetylation at Lys-70 seems to increase chaperone activity
undergoes age-dependent proteolytical cleavage at the C-terminus
alpha-crystallin A(1-172) is the most predominant form produced most rapidly during the first 12 years of age; after this is present in ~50% of lens molecules

O-glycosylated; contains N-acetylglucosamine side chains
heteropolymer composed of three CRYAA & one CRYAB subunits
inter-subunit bridging via Zn+2 enhances stability, which is crucial as there is no protein turn over in the lens
can also form homodimers & higher homooligomers
age-dependent C-terminal truncation affects oligomerization
belongs to the small heat shock protein (HSP20) family