Differential phosphorylation of alpha-A crystallin in human lens of different age.
Previous studies have demonstrated that a major site of in vivo phosphorylation of alpha-A crystallin from human lens is serine-122. To determine the relative degree of this phosphorylation in alpha-A crystallin from human lenses of different age, alpha-A crystallin was purified from total lens proteins, followed by sequential digestion with lys-C and asp-N endoproteases. Mass spectral analysis of the asp-N peptide fragments that contained serine-122 demonstrated undetectable levels of phosphorylation from infant human lenses (41 days, 2 months and 4 months of age). Identical analysis of alpha-A crystallin from older lenses (12, 15, 40 and 73 years of age) indicated significant phosphorylation of serine-122, demonstrating that phosphorylation of the serine-122 residue of alpha-A crystallin does not occur during the aging process, but is rather a developmentally regulated event in the human lens.
Takemoto
L J
LJ
Division of Biology, Kansas State University, Manhattan 66506, USA.
D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging; D002648:Child; D003459:Crystallins / Q000737:chemistry*; D006801:Humans; D007223:Infant; D007908:Lens, Crystalline / Q000737:chemistry*; D010766:Phosphorylation
D003459:Crystallins