PhosphoSite: A bioinformatics resource dedicated to physiological protein phosphorylation

Hornbeck, Peter; Chabra, Indy; Kornhauser, Jon M.; Skrzypek, Elźbieta; Zhang, Bin

doi:10.1002/pmic.200300772

Cited by 518 publications

(504 citation statements)

References 25 publications

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“…4), and tandem mass spectra are available in the PRIDE database under accession number 9777. All except one of the phosphotyrosine peptides that were identified have been reported before and can be found in the PhosphoSitePlus database (37). The observed temporal ratio profiles largely clustered into three groups (Fig.…”

Section: Resultsmentioning

confidence: 71%

In-depth Qualitative and Quantitative Profiling of Tyrosine Phosphorylation Using a Combination of Phosphopeptide Immunoaffinity Purification and Stable Isotope Dimethyl Labeling

Boersema

Foong

Ding

et al. 2010

Molecular & Cellular Proteomics

158

123

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Several mass spectrometry-based assays have emerged for the quantitative profiling of cellular tyrosine phosphorylation. Ideally, these methods should reveal the exact sites of tyrosine phosphorylation, be quantitative, and not be cost-prohibitive. The latter is often an issue as typically several milligrams of (stable isotope-labeled) starting protein material are required to enable the detection of low abundance phosphotyrosine peptides. Here, we adopted and refined a peptidecentric immunoaffinity purification approach for the quantitative analysis of tyrosine phosphorylation by combining it with a cost-effective stable isotope dimethyl labeling method. We were able to identify by mass spectrometry, using just two LC-MS/MS runs, more than 1100 unique non-redundant phosphopeptides in HeLa cells from about 4 mg of starting material without requiring any further affinity enrichment as close to 80% of the identified peptides were tyrosine phosphorylated peptides. Stable isotope dimethyl labeling could be incorporated prior to the immunoaffinity purification, even for the large quantities (mg) of peptide material used, enabling the quantification of differences in tyrosine phosphorylation upon pervanadate treatment or epidermal growth factor stimulation. Analysis of the epidermal growth factor-stimulated HeLa cells, a frequently used model system for tyrosine phosphorylation, resulted in the quantification of 73 regulated unique phosphotyrosine peptides. The quantitative data were found to be exceptionally consistent with the literature, evidencing that such a targeted quantitative phosphoproteomics approach can provide reproducible results. In general, the combination of immunoaffinity purification of tyrosine phosphorylated peptides with large scale stable isotope dimethyl labeling provides a cost-effective approach that can alleviate variation in sample preparation and analysis as samples can be combined early on. Using this approach, a rather complete qualitative and quantitative picture of tyrosine phosphorylation signaling events can be generated. Molecular & Cellular Proteomics 9:84 -99, 2010.

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Section: Resultsmentioning

confidence: 71%

In-depth Qualitative and Quantitative Profiling of Tyrosine Phosphorylation Using a Combination of Phosphopeptide Immunoaffinity Purification and Stable Isotope Dimethyl Labeling

Boersema

Foong

Ding

et al. 2010

Molecular & Cellular Proteomics

158

123

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“…be phosphorylated in vivo [38,39]. However, BMAL1 Ser78 is also very likely to undergo phosphorylation predicted by NetPhos 2.0 Server [40], which is supported by the finding of a mass spectrometry record of phosphorylated BMAL1 Ser78 in PhosphoSite database [41]. To compare the effects of the four serine residues on phosphorylation-mediated DNA-binding inhibition, we mutated them to phospho-mimicking glutamate residues individually and measured the binding affinities of corresponding heterodimeric proteins to WT DNA.…”

Section: Potential Phosphorylation Sites In Basic Regionsmentioning

confidence: 99%

Intermolecular recognition revealed by the complex structure of human CLOCK-BMAL1 basic helix-loop-helix domains with E-box DNA

Wang

et al. 2012

Cell Res

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CLOCK (circadian locomotor output cycles kaput) and BMAL1 (brain and muscle ARNT-like 1) are both transcription factors of the circadian core loop in mammals. Recently published mouse CLOCK-BMAL1 bHLH (basic helix-loop-helix)-PAS (period-ARNT-single-minded) complex structure sheds light on the mechanism for heterodimer formation, but the structural details of the protein-DNA recognition mechanisms remain elusive. Here we have elucidated the crystal structure of human CLOCK-BMAL1 bHLH domains bound to a canonical E-box DNA. We demonstrate that CLOCK and BMAL1 bHLH domains can be mutually selected, and that hydrogen-bonding networks mediate their E-box recognition. We identified a hydrophobic contact between BMAL1 Ile80 and a flanking thymine nucleotide, suggesting that CLOCK-BMAL1 actually reads 7-bp DNA and not the previously believed 6-bp DNA. To find potential non-canonical E-boxes that could be recognized by CLOCK-BMAL1, we constructed systematic single-nucleotide mutations on the E-box and measured their relevant affinities. We defined two non-canonical E-box patterns with high affinities, AACGTGA and CATGTGA, in which the flanking A7-T7′ base pair is indispensable for recognition. These results will help us to identify functional CLOCK-BMAL1-binding sites in vivo and to search for clock-controlled genes. Furthermore, we assessed the inhibitory role of potential phosphorylation sites in bHLH regions. We found that the phospho-mimicking mutation on BMAL1 Ser78 could efficiently block DNA binding as well as abolish normal circadian oscillation in cells. We propose that BMAL1 Ser78 should be a key residue mediating input signal-regulated transcriptional inhibition for external cues to entrain the circadian clock by kinase cascade.

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“…Reported protein interactions were collected from the following protein-protein interaction databases: Human Protein Reference Database (29) and STRING (30). Reported phosphorylation data was obtained from Phospho.ELM (31,32) and PhosphoSite (33).…”

Section: Methodsmentioning

confidence: 99%

SH2 Domains Recognize Contextual Peptide Sequence Information to Determine Selectivity

Liu¹,

Jablonowski²,

Shah³

et al. 2010

Molecular & Cellular Proteomics

106

137

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Selective ligand recognition by modular protein interaction domains is a primary determinant of specificity in signaling pathways. Src homology 2 (SH2) domains fulfill this capacity immediately downstream of tyrosine kinases, acting to recruit their host polypeptides to ligand proteins harboring phosphorylated tyrosine residues. The degree to which SH2 domains are selective and the mechanisms underlying selectivity are fundamental to understanding phosphotyrosine signaling networks. An examination of interactions between 50 SH2 domains and a set of 192 phosphotyrosine peptides corresponding to physiological motifs within FGF, insulin, and IGF-1 receptor pathways indicates that individual SH2 domains have distinct recognition properties and exhibit a remarkable degree of selectivity beyond that predicted by previously described binding motifs. The underlying basis for such selectivity is the ability of SH2 domains to recognize both permissive amino acid residues that enhance binding and non-permissive amino acid residues that oppose binding in the vicinity of the essential phosphotyrosine. Neighboring positions affect one another so local sequence context matters to SH2 domains. This complex linguistics allows SH2 domains to distinguish subtle differences in peptide ligands. This newly appreciated contextual dependence substantially increases the accessible information content embedded in the peptide ligands that can be effectively integrated to determine binding. This concept may serve more broadly as a paradigm for subtle recognition of physiological ligands by protein interaction domains. Molecular & Cellular Proteomics 9:2391-2404, 2010. The Src homology 2 (SH2)1 domain is the classic archetype for the large family of modular protein interaction domains that serve to organize a diverse array of cellular processes. As its name suggests, the SH2 domain was identified in the regulatory regions of non-receptor protein-tyrosine kinases (PTKs) of the Src family (1). The human genome encodes 110 SH2 domain proteins (2) that represent the primary mechanism for cellular signal transduction immediately downstream of PTKs. SH2 domains interact with phosphorylated tyrosinecontaining peptide sequences (3-6). In doing so, they couple activated PTKs to intracellular pathways that regulate many aspects of cellular communication in metazoans (7,8). In this manner, SH2 domains function alongside PTKs and proteintyrosine phosphatases to direct specificity in phosphotyrosine signaling. SH2 domain proteins play a critical role in development and have been linked to a wide range of human diseases including cancers, diabetes, and immunodeficiencies (2).Activation and recruitment of PTKs and protein-tyrosine phosphatases can control the spatial and temporal organization of phosphotyrosine signaling. However, signaling specificity in terms of downstream targets is entirely determined by phosphotyrosine-mediated recruitment events for which SH2 domains are responsible. Therefore, the binding selectivity of SH2 domains is critical for ...

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PhosphoSite: A bioinformatics resource dedicated to physiological protein phosphorylation

Cited by 518 publications

References 25 publications

In-depth Qualitative and Quantitative Profiling of Tyrosine Phosphorylation Using a Combination of Phosphopeptide Immunoaffinity Purification and Stable Isotope Dimethyl Labeling

In-depth Qualitative and Quantitative Profiling of Tyrosine Phosphorylation Using a Combination of Phosphopeptide Immunoaffinity Purification and Stable Isotope Dimethyl Labeling

Intermolecular recognition revealed by the complex structure of human CLOCK-BMAL1 basic helix-loop-helix domains with E-box DNA

SH2 Domains Recognize Contextual Peptide Sequence Information to Determine Selectivity

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