Protein tag
A protein tag, also known as a fusion tag or an affinity tag, is a short peptide sequence that is genetically fused to a target protein. The addition of a protein tag to a protein of interest aims to facilitate its purification, detection, localization, and/or characterization, making protein tags invaluable tools in Molecular biology and Biotechnology research.
History[edit | edit source]
The concept of protein tags emerged in the early 1980s, addressing the challenge of isolating and studying specific proteins efficiently. The pioneering protein tag developed was the hexahistidine tag (His-tag), comprising six consecutive histidine residues with a high affinity for metal ions like nickel or cobalt. Subsequently, a diverse array of protein tags have been developed, each offering unique properties and applications.
Purpose[edit | edit source]
Protein tags are versatile tools serving multiple roles in protein research:
- Purification: Tags like the His-tag, glutathione S-transferase (GST) tag, and streptavidin-binding peptide (SBP) tag enable the efficient purification of tagged proteins from complex mixtures.
- Detection: Detection and quantification are facilitated by tags such as the green fluorescent protein (GFP) tag, FLAG tag, and hemagglutinin (HA) tag, which are recognizable by specific antibodies or reagents.
- Localization: Fluorescent protein tags (e.g., GFP, mCherry) allow researchers to observe the subcellular distribution of proteins in live cells via fluorescence microscopy.
- Characterization: Tags such as the maltose-binding protein (MBP) tag and calmodulin-binding peptide (CBP) tag help explore protein structure, function, and interactions.
Commonly Used Protein Tags[edit | edit source]
The scientific community frequently utilizes several protein tags due to their effectiveness and adaptability:
- His-tag: Binds to metal ions for purification via immobilized metal affinity chromatography (IMAC).
- GST-tag: Derived from the glutathione S-transferase enzyme, it facilitates affinity purification.
- FLAG-tag: A small peptide sequence used extensively for detection and immunoprecipitation.
- GFP-tag: Allows visualization of proteins in live cells through fluorescence microscopy.
- HA-tag: Derived from influenza virus hemagglutinin, useful for detection and immunoprecipitation.
Categories[edit | edit source]
Protein tags can be categorized by their properties and applications:
- 1. Affinity Tags: Facilitate purification through specific binding interactions. Examples: His-tag, GST-tag, SBP-tag.
- 2. Fluorescent Tags: Enable visualization via fluorescence microscopy. Examples: GFP-tag, mCherry-tag.
- 3. Epitope Tags: Recognized by specific antibodies for detection and immunoprecipitation. Examples: FLAG-tag, HA-tag.
- 4. Enzyme Tags: Derived from enzymes, these tags have diverse applications, such as in protein-protein interaction studies. Examples: MBP-tag, CBP-tag.
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External links[edit source]
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