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Phosphoproteins with Stability against All Urinary Phosphatases as Potential Biomarkers in Urine
Author(s) -
Zhao Mindi,
Gao Youhe
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.567.4
Subject(s) - urine , phosphorylation , chemistry , urinary system , phosphatase , protein phosphorylation , biomarker , biomarker discovery , proteomics , biochemistry , biology , endocrinology , protein kinase a , gene
Urine, by accumulating all kinds of changes, was proposed to be a better source for biomarker discovery. As one of the most common post‐translational modifications, phosphorylation plays a vital role in many biological activities. However, the urine phosphoproteome has been largely neglected due to the low abundance of phosphoproteins and the presence of various phosphatases in urine. The low level of background phosphorylation in urine is actually advantageous, as urinary phosphopeptides/proteins that are stable to the phosphatases present in urine have the potential to serve as valuable disease biomarkers. Using a TiO2 enrichment strategy, this study aimed to create a comprehensive proteomic profile of human urinary phosphoproteins and to characterize the changes in the urine phosphoproteome after incubation of urine with cell lysates. In total, 106 phosphorylation sites corresponding to 64 proteins, including 80 previously unidentified human urine protein phosphorylation sites, were identified by mass spectrometry. Fifteen phosphopeptides, together averaging 47% of the total phosphopeptides, were found in samples from all individuals. Addition of cellular proteins to urine did not significantly change the phosphorylation level of urine proteins. But there were still a few phosphopeptides from cell lysates survived urinary phosphatases; such phosphopeptides represent potential biomarkers in urine.