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In vivo acetylation identified at lysine 70 of human lens αA‐crystallin
Author(s) -
Lin Peiping P.,
Barry Richard C.,
Smith David L.,
Smith Jean B.
Publication year - 1998
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560070622
Subject(s) - crystallin , acetylation , lysine , chemistry , biochemistry , posttranslational modification , chaperone (clinical) , molecular mass , biophysics , electrospray ionization , mass spectrometry , stereochemistry , chromatography , biology , enzyme , amino acid , medicine , pathology , gene
Posttranslational modification of protein lysyl residues that change the net charge of the molecule may alter the protein conformation. Such modifications are of particular significance among lens proteins, because conformational changes are associated with the development of cataract. A previously unidentified acetylated form of αA‐crystallin has been isolated from the water‐soluble portion of human lenses. The αA‐crystallins were fractionated by anion exchange HPLC into seven peaks, each containing more than one form of αA‐crystallin. The previously reported deamidated and phosphorylated forms were identified by their molecular masses, determined by electrospray ionization mass spectrometry. In addition to these modifications, approximately 5% of αA‐crystallin had a modification that decreased the charge by one and increased the molecular mass by 42 u. This modification, identified as acetylation, was located uniquely at Lys 70. Like any modification that alters the surface charge, acetylation may affect protein conformation and intermolecular interactions, thereby altering the solubility or chaperone properties of αA‐crystallin. Acetylation of lysine 70 is potentially significant since it is located in a region that has been implicated in the chaperone activity of αA‐crystallin.