Parts of them are used as epitope tags
Epitope tags, i.e. short peptide tags are commonly used, versatile, and convenient tools for multiple capture and detection applications including immunofluorescence, immunoprecipitation, affinity purification, and Western blotting.
Among those epitope tags, several tags are from virus protein origin, because they likely have unique sequences. Hence, they might have less issues with cross reactivity of antibodies potentially detecting host cell protein background.
Below, an overview of peptide tags that are of virus origin is shown:
-
E2 tag / E2 epitope tag
Applications: Detection and purification
Sequence: SSTSSDFRDR
Size: 10 AA, 1.2 kDa
Tag location: N-, C-terminal or internal
Origin: transactivator protein E2 of bovine papilloma-virus type-1 -
HA tag
Applications: Purification and detection
Sequence: YPYDVPDYA
Size: 9 AA, 1.1 kDa
Tag location: N-, C-terminal or internal
Origin: amino acids 98–106 of the major surface protein glycoprotein hemagglutinin of influenza virus
Comment: Not suitable for detection or purification of proteins from apoptotic cells because it is cleaved by Caspase-3 / Caspase-7 -
HSV tag
Applications: Purification
Sequence: QPELAPEDPED
Size: 11 AA, 1.2 kDa
Tag location: C-terminal
Origin: aa 290–300 of glycoprotein D, a major surface protein of herpes simplex virus type 1 (HSV-1) -
T7 tag
Applications: Purification and increased expression
Sequence: MASMTGGQQMG
Size: 11 AA, 1.2 kDa
Tag location: N-, C-terminal or internal
Origin: N-terminal 11 residues of the major capsid protein gp 10 of T7 phage -
VSV-G-tag
Applications: Detection and purification
Sequence: YTDIEMNRLGK
Size: 11 AA, 1.3 kDa
Tag location: C-terminal
Origin: C terminal aa of virus envelope glycoprotein of vesicular stomatitis virus G -
V5-tag
Sequence: GKPIPNPLLGLDST
Size: 14 AA, 1.4 kDa
Tag location: N-, C-terminal or internal
Origin: P and V proteins of Simian virus 5 (SV5) of the Rubulavirus genus in the Paramyxoviridae family
References
Kimple, M.E. et al (2013): Overview of Affinity Tags for Protein Purification
Curr Protoc Protein Sci. 2013; 73: Unit–9.9, DOI 10.1002/0471140864.ps0909s73
and references therein
Boriana Marintcheva, B. (2018) in Harnessing the Power of Viruses, chapter: Viral Tools for Protein Expression and Purification, Academic Press, DOI 10.1016/C2015-0-05654-4
Terpe, K. (2003): Overview of tag protein fusions: from molecular and biochemical fundamentals to commercial systems, Appl Microbiol Biotechnol. 60:523–533, DOI 10.1007/s00253-002-1158-6
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