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Human influenza hemagglutinin (HA) is a surface glycoprotein required for the infectivity of the human influenza virus. The HA tag is derived from the HA-molecule corresponding to amino acids 98-106. It has been extensively used as a general epitope tag in expression vectors. Many recombinant proteins have been engineered to express the HA tag, which does not appear to interfere with the bioactivity or the biodistribution of the recombinant protein. This tag facilitates the detection, isolation, and purification of the protein of interest.[1]

The HA tag is not suitable for detection or purification of proteins from apoptotic cells since it is cleaved by Caspase-3 and / or Caspase-7 after its sequence DVPD, causing it to lose its immunoreactivity.[2] Labeling of endogenous proteins with HA-tag using CRISPR was recently accomplished in-vivo in differentiated neurons.[3]


The DNA sequences for the HA-tag include: 5' TAC CCA TAC GAT GTT CCA GAT TAC GCT 3' or 5' TAT CCA TAT GAT GTT CCA GAT TAT GCT 3'

The resulting amino acid sequence: YPYDVPDYA (Tyr-Pro-Tyr-Asp-Val-Pro-Asp-Tyr-Ala).

See also[edit]


  1. ^ "Anti-HA Tag Antibody Updated 28/10/2021". Merck Millipore.{{cite web}}: CS1 maint: url-status (link)
  2. ^ Schembri L, Dalibart R, Tomasello F, Legembre P, Ichas F, De Giorgi F (February 2007). "The HA tag is cleaved and loses immunoreactivity during apoptosis". Nature Methods. 4 (2): 107–8. doi:10.1038/nmeth0207-107. PMID 17264856.
  3. ^ Mikuni T, Nishiyama J, Sun Y, Kamasawa N, Yasuda R. "High Throughput, High Resolution Mapping of Protein Localization in Mammalian Brain by In Vivo Genome Editing". Cell. 165 (7): 1803–1817. doi:10.1016/j.cell.2016.04.044. PMC 4912470. PMID 27180908.

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