Contributes to the transparency and refractive index of the lens (PubMed:18302245). In its oxidized form (absence of intramolecular disulfide bond), acts as a chaperone, preventing aggregation of various proteins under a wide range of stress conditions (PubMed:22120592, PubMed:31792453, PubMed:18199971, PubMed:19595763). Required for the correct formation of lens intermediate filaments as part of a complex composed of BFSP1, BFSP2 and CRYAA (PubMed:28935373). Heteropolymer composed of three CRYAA and one CRYAB subunits (PubMed:20836128). Inter-subunit bridging via zinc ions enhances stability, which is crucial as there is no protein turn over in the lens (PubMed:22890888). Can also form homodimers and homotetramers (dimers of dimers) which serve as the building blocks of homooligomers (PubMed:17909943, PubMed:31792453, PubMed:23255486). Within homooligomers, the zinc-binding motif is created from residues of 3 different molecules. His-100 and Glu-102 from one molecule are ligands of the zinc ion, and His-107 and His-154 residues from additional molecules complete the site with tetrahedral coordination geometry (By similarity). Part of a complex required for lens intermediate filament formation composed of BFSP1, BFSP2 and CRYAA (PubMed:28935373). Translocates to the nucleus during heat shock and resides in sub-nuclear structures known as SC35 speckles or nuclear splicing speckles. Expressed in the eye lens (at protein level). O-glycosylated; contains N-acetylglucosamine side chains. Deamidation of Asn-101 in lens occurs mostly during the first 30 years of age, followed by a small additional amount of deamidation (approximately 5%) during the next approximately 38 years, resulting in a maximum of approximately 50% deamidation during the lifetime of the individual. Phosphorylation on Ser-122 seems to be developmentally regulated. Absent in the first months of life, it appears during the first 12 years of human lifetime. The relative amount of phosphorylated form versus unphosphorylated form does not change over the lifetime of the individual. Acetylation at Lys-70 may 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 and after this age is present in approximately 50% of the lens molecules. In young individuals and during the first approximately 30 years of life, less than half molecules contain an intramolecular disulfide bond (oxidized form), while in the remaining fraction the cysteines are in the free sulfhydryl form (reduced form). With aging, the amount of oxidized form increases up to 90% and it becomes a major constituent of high molecular weight aggregates, concomitant with an age-dependent loss of its chaperone activity. The reduced form is undetectable in cataractous lenses. With 1 phosphate group. Alpha-crystallin A 1-172 is found at nearly twofold higher levels in diabetic lenses than in age-matched control lenses. The disease is caused by variants affecting the gene represented in this entry. Belongs to the small heat shock protein (HSP20) family.