affinity tag
Definition
An affinity tag is a short peptide or protein sequence genetically fused to a target protein to facilitate its purification, detection, and characterization. Common affinity tags include His-tag (polyhistidine), FLAG-tag, GST (glutathione S-transferase), and MBP (maltose-binding protein). These tags bind specifically to complementary ligands immobilized on chromatography resins, enabling rapid protein isolation from complex cellular lysates. Affinity tags are essential tools in proteomics research, allowing scientists to study protein expression, localization, interactions, and post-translational modifications. They can be placed at N-terminus, C-terminus, or internal positions, and are often designed with protease cleavage sites for subsequent removal. The choice of tag depends on experimental requirements including protein solubility, expression levels, and downstream applications.
Visualize affinity tag in Nodes Bio
Researchers can visualize protein-protein interaction networks derived from affinity purification-mass spectrometry (AP-MS) experiments in Nodes Bio. By mapping tagged proteins as central nodes, users can explore direct binding partners, identify protein complexes, and analyze functional modules. Network visualization reveals how affinity-tagged bait proteins connect to prey proteins, helping researchers understand cellular pathways and validate interaction specificity across different experimental conditions.
Visualization Ideas:
- Protein-protein interaction networks from AP-MS experiments showing bait-prey relationships
- Comparative networks displaying interaction differences between wild-type and mutant tagged proteins
- Multi-layer networks integrating affinity purification data with gene expression and pathway annotations
Example Use Case
A cancer research team investigating the role of mutant p53 in tumor progression uses FLAG-tagged p53 variants expressed in cancer cell lines. Following affinity purification and mass spectrometry, they identify 150 potential binding partners. By visualizing this interaction network in Nodes Bio, they discover that mutant p53 preferentially binds to chromatin remodeling complexes rather than DNA repair proteins, revealing a gain-of-function mechanism. The network analysis highlights novel therapeutic targets and explains why certain p53 mutations correlate with aggressive tumor phenotypes and treatment resistance.