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Identification of the posttranslational modifications of bovine lens αB‐crystallins by mass spectrometry
Author(s) -
Smith Jean B.,
Sun Yiping,
Smith David L.,
Green Brian
Publication year - 1992
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.5560010506
Subject(s) - mass spectrometry , crystallin , chemistry , protein mass spectrometry , phosphorylation , chromatography , size exclusion chromatography , fast atom bombardment , molecular mass , electrospray ionization , bottom up proteomics , biochemistry , sample preparation in mass spectrometry , peptide sequence , gene , enzyme
A combination of mass spectrometric techniques has been used to investigate the amino acid sequence and post‐translational modifications of αB‐crystallin isolated from bovine lenses by gel filtration chromatography and reversed‐phase high performance liquid chromatography. Chromatographic fractions were analyzed by electrospray ionization mass spectrometry to determine the homogeneity and molecular weights of proteins in the fractions. The αB‐crystallin primary gene product, its mono‐ and diphosphorylated forms, its N‐ and C‐terminal truncated forms, as well as other lens proteins unrelated to the αB‐crystallins were identified by their molecular weights. Detailed information about the sites of phosphorylation, as well as evidence supporting reassignment of Asn to Asp at position 80, was obtained by analyzing proteolytic digests of these proteins by fast atom bombardment mass spectrometry. Results of this investigation indicate that αB‐crystallin is phosphorylated in vivo at Ser 45, Ser 59, and either Ser 19 or 21. From the specificity of phosphorylation of α‐crystallins, it appears that there may be two different kinases responsible for their phosphorylation.