The name of this superfamily has been modified since the most recent official CATH+ release (v4_3_0). At the point of the last release, this superfamily was: waiting to be named.
The haemagglutinin glycoprotein is a trimer containing three structurally distinct regions: a globular head consisting of anti-parallel beta-sheets that form a beta-sandwich with a jelly-roll fold (contains the receptor binding site and the HA1/HA2 cleavage site); a triple-stranded, coiled-coil, alpha-helical stalk; and a globular foot composed of anti-parallel beta-sheets. Each monomer consists of an intact HA0 polypeptide with the HA1 and HA2 regions linked by disulphide bonds. The N-terminus of HA1 provides the central strand in the 5-stranded globular foot, while the rest of the HA1 chain makes its way to the 8-stranded globular head. HA2 provides two alpha helices, which form part of the triple-stranded coiled-coil that stabilises the trimer, its C-terminus providing the remaining strands of the 5-stranded globular foot. HA1 is less conserved among different HA subtypes, unlike HA2 which is the primary target for universal vaccines.
This superfamily represents a subdomain of the HA1 peptide that occurs following HA0 cleavage. This subdomain has an alpha/beta structure.
|Domain clusters (>95% seq id):||72|
|Domain clusters (>35% seq id):||7|
|Structural Clusters (5A):||1|
|Structural Clusters (9A):||1|