Haemagglutinin peptide

Haemagglutinin (HA) peptide YPYDVPDYA – HA Tag is a well characterized 9 amino acids synthetic peptide deriving from an epitope of the original influenza hemagglutinin protein. Haemagglutinin (HA) (UniProt : P03437) is an envelope protein present in the viral membrane of influenza viruses. HA forms a trimer containing structurally distinct regions and an intact HA0 polypeptide composed of two subunits, called HA1 and HA2, connected by one disulfide bridge. To initiate their fusion with their cellular hosts, influenza viruses first bind to sialic acids at the surface of respiratory epithelial cells. Following this interaction, they will enter the cell via endocytosis. Due to proton pumps on the endosome’s membrane, the lumen will acidify under pH=6, cleaving HA1 from HA0 and thus freeing the N-terminal of HA2. This will allow HA2 anchoring to the host’s endosome, fusing the viral envelope to the endosome membrane to enable genome exchange and later viral multiplication. HA synthetic peptide can be used for various applications. When coupled to a protein carrier, such as KLH, YPYDVPDYA is able to stimulate a host humoral immune response to generate monoclonal and polyclonal antibodies. In this case, the resulting antibodies are called « anti-tag antibodies », whose aim is to optimize the detection and the purification of HA-tagged proteins. More than the production of highly sensitive and specific anti-HA antibodies, YPYDVPDYA is used to compete with the latter to confirm binding specificity. This feature is also employed for HA-tagged protein purification to elute the protein of interest from affinity column of monoclonal anti-HA agarose.