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Post-translational modifications of proteins control many biological processes, and examining their diversity is critical for understanding mechanisms of cell regulation. Mass spectrometry is a fundamental tool for detecting and mapping covalent modifications and quantifying their changes. Modern approaches have made large-scale experiments possible,(More)
A major event in the keratinization of epidermis is the production of the histidine-rich protein filaggrin (26,000 mol wt) from its high molecular weight (greater than 350,000) phosphorylated precursor (profilaggrin). We have identified two nonphosphorylated intermediates (60,000 and 90,000 mol wt) in NaSCN extracts of epidermis from C57/Bl6 mice by in vivo(More)
This tutorial article introduces mass spectrometry (MS) for peptide fragmentation and protein identification. The current approaches being used for protein identification include top-down and bottom-up sequencing. Top-down sequencing, a relatively new approach that involves fragmenting intact proteins directly, is briefly introduced. Bottom-up sequencing, a(More)
Urothelial plaques consist of four major uroplakins (Ia, Ib, II, and III) that form two-dimensional crystals covering the apical surface of urothelium, and provide unique opportunities for studying membrane protein assembly. Here, we describe a novel 35-kD urothelial plaque-associated glycoprotein that is closely related to uroplakin III: they have a(More)
Functional proteomics provides a powerful approach to screen for alterations in protein expression and posttranslational modifications under conditions of human disease. In this study, we use protein screening to examine markers of melanoma progression, by profiling melanocyte versus melanoma cell lines using two-dimensional electrophoresis and mass(More)
Mps1 is one of the several essential kinases whose activation is required for robust mitotic spindle checkpoint signalling. The activity of Mps1 is tightly regulated and increases dramatically during mitosis or in response to spindle damage. To understand the molecular mechanism underlying Mps1 regulation, we determined the crystal structure of the kinase(More)
Phototransduction is a canonical G protein-mediated cascade of retinal photoreceptor cells that transforms photons into neural responses. Phosducin (Pd) is a Gbetagamma-binding protein that is highly expressed in photoreceptors. Pd is phosphorylated in dark-adapted retina and is dephosphorylated in response to light. Dephosphorylated Pd binds Gbetagamma(More)
One of the final events in cornification of epidermal cells is processing of profilaggrin to the keratin-associated protein filaggrin. Processing involves several proteolytic events and occurs in two discrete proteolytic stages (Resing, K. A., Walsh, K. A., and Dale, B. A. (1984) J. Cell Biol. 99, 1372-1378; Resing, K. A., Walsh, K. A., Haugen-Scofield, J.,(More)
When analyzing proteins in complex samples using tandem mass spectrometry of peptides generated by proteolysis, the inference of proteins can be ambiguous, even with well-validated peptides. Unresolved questions include whether to show all possible proteins vs a minimal list, what to do when proteins are inferred ambiguously, and how to quantify peptides(More)