PTM Identification and Quantification

APTBIO supplies LC-MS/MS methods for analyzing various post-translational modifications. Using our highly sensitive tandem mass spectrometry, we can help you accurately and efficiently identify the modification and position of the modified amino acid residue. 


The following are the common types of Post-translational Modifications:

▶ Phosphorylation is a post-translational modification of proteins in which an amino acid residue is phosphorylated by a protein kinase by the addition of a covalently bound phosphate group. Phosphorylation alters the structural conformation of a protein, causing it to become activated, deactivated, or modifying its function.


Phosphorylation peptides enrichment methods: TiO2 or IMAC.


▶ N-glycosylation is the attachment of the sugar molecular oligosaccharide known as glycan to a nitrogen atom. This type of linkage is important for both the structure and function of some eukaryotic proteins. The N-linked glycosylation process occurs in eukaryotes and widely in archaea, but very rarely in bacteria. The nature of N-linked glycans attached to a glycoprotein is determined by the protein and the cell in which it is expressed. It also varies across species. Different species synthesize different types of N-linked glycan.


The different types of glycans produced in different organisms. (From Wikipedia)

N-glycosylation peptides enrichment method: lectin.


▶ Acetylation is an important modification of proteins in cell biology; and proteomics studies have identified thousands of acetylated mammalian proteins. Acetylation occurs as a co-translational and post-translational modification of proteins, for example, histones, p53 and tubulins. Among these proteins, chromatin proteins and metabolic enzymes are highly represented, indicating that acetylation has a considerable impact in gene expression and metabolism.


Acetylation peptides enrichment method: Anti-Ac-Kantibody beads (PTMScan Acetyl-Lysine Motif (Ac-K) Kit, Cell Signal Technology)


▶ Ubiquitination is an enzymatic process that involves the bonding of an ubiquitin protein to a substrate protein. Ubiquitination affects proteins in many ways: it can mark them for degradation via the proteasome, alter their cellular location, affect their activity, and promote or prevent protein interaction. Ubiquitination involves three main steps: activation, conjugation and ligation performed by ubiquitin-activating enzymes (E1), ubiquitin-conjugating enzymes (E2) and ubiquitin ligases (E3) respectively.


Ubiquitination peptides enrichment method: Anti-K-ε-GG antibody beads (PTMScan Ubiquitin Remnant Motif (K-ε-GG) kit, Cell Signal Technology)


▶ Methylation typically takes place on arginine or lysine amino acid residues in the protein sequence. Arginine can be methylated once (monomethylated arginine) or twice, with either both methyl groups on one terminal nitrogen (asymmetric dimethylarginie) or one on both nitrogens (symmetric dimethylarginie), by protein arginine methyltransferases. Lysine can be methylated once, twice, or three times by lysine methyltransferases. Protein methylation has been most studied in the histones. The transfer of methyl groups from S-adenosyl methionine to histone is catalyzed by enzymes known as histone methyltransferases. Histones that are methylated on certain residues can act epigenetically to repress or activate gene expression. Protein methylation is one type of post-translational modification.


Methylation peptides enrichment method: PTMScan beads from Cell Signal Technology.

▶ Other Acylation


Bioinformatics analysis:

1) Modification proteins qualification results

2) Modification peptides qualification and quantification results

3) Differentially expressed modification proteins GO analysis

4) Differentially expressed modification proteins KEGG analysis

5) Differentially expressed modification proteins GO enrichment analysis

6) Differentially expressed modification proteins KEGG enrichment analysis

7) Differentially expressed modification peptides cluster analysis

8) Modification sites motif analysis

9) Differentially expressed modification proteins PPI analysis

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