Human influenza hemagglutinin (HA) is a surface

glycoprotein Glycoproteins are proteins which contain oligosaccharide chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycos ...

required for the infectivity of the human

influenza virus ''Orthomyxoviridae'' (from Greek ὀρθός, ''orthós'' 'straight' + μύξα, ''mýxa'' 'mucus') is a family of negative-sense RNA viruses. It includes seven genera: ''Alphainfluenzavirus'', ''Betainfluenzavirus'', '' Gammainfluenzavirus'', ' ...

. The HA-tag is derived from the HA-molecule corresponding to

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...

s 98-106. HA-tag has been extensively used as a general epitope tag in

expression vector An expression vector, otherwise known as an expression construct, is usually a plasmid or virus designed for gene expression in cells. The vector is used to introduce a specific gene into a target cell, and can commandeer the cell's mechanism for ...

s. Many

recombinant protein Recombinant DNA (rDNA) molecules are DNA molecules formed by laboratory methods of genetic recombination (such as molecular cloning) that bring together genetic material from multiple sources, creating sequences that would not otherwise be fou ...

s have been engineered to express the HA-tag, which does not generally appear to interfere with the

bioactivity In pharmacology, biological activity or pharmacological activity describes the beneficial or adverse effects of a drug on living matter. When a drug is a complex chemical mixture, this activity is exerted by the substance's active ingredient or ...

or the biodistribution of the recombinant protein. This tag facilitates the detection, isolation and purification of the protein of interest. The HA-tag is not suitable for detection or purification of proteins from

apoptotic Apoptosis (from grc, ἀπόπτωσις, apóptōsis, 'falling off') is a form of programmed cell death that occurs in multicellular organisms. Biochemical events lead to characteristic cell changes ( morphology) and death. These changes incl ...

cells since it is cleaved by

Caspase-3 Caspase-3 is a caspase protein that interacts with caspase-8 and caspase-9. It is encoded by the ''CASP3'' gene. ''CASP3'' orthologs have been identified in numerous mammals for which complete genome data are available. Unique orthologs are also p ...

and / or

Caspase-7 Caspase-7, apoptosis-related cysteine peptidase, also known as CASP7, is a human protein encoded by the ''CASP7'' gene. ''CASP7'' orthologs have been identified in nearly all mammals for which complete genome data are available. Unique orthologs a ...

after its sequence DVPD, causing it to lose its

immunoreactivity An immunoassay (IA) is a biochemical test that measures the presence or concentration of a macromolecule or a small molecule in a solution through the use of an antibody (usually) or an antigen (sometimes). The molecule detected by the immunoassay ...

. Labeling of endogenous proteins with HA-tag using CRISPR was recently accomplished in-vivo in differentiated

neuron A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. N ...

Sequence

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).

Sequence

See also

References

Further reading