Only 1 basic amino acid
(PQIATR*G) was found at the HA cleavage site of A/canine/Taiwan/E01/2014.
4% which were far lower than % TNAA, whilst the percentage range in total basic amino acid
(TBAA) was 15.
It may be a basic amino acid
or provide special space structure to recognize ZE2.
Shaped like the letter "C," these compounds wrap around chains of lysine, a basic amino acid
that is a constituent of most proteins.
When a basic amino acid
is in an acidic medium (having a pH lower than 7 and containing the hydrogen ion [H.
7]) B, where B is arginine or lysine, and X is any non-acidic amino acid; there is also at least one additional basic amino acid
within, or adjacent to, the basic unit (7, 8).
The HA gene of KU-08 contained multiple basic amino acid
insertions at the HA cleavage site (SPQRERRRKKRR), similar to those found at the HA cleavage site for other viruses characterized from Thailand during this time.
The HA gene of KU-02 and KU-03 contained multiple basic amino acid
insertions at the HA cleavage site (SPQRERRRKKRR) as well as glutamine and glycine (Q222-G224) at the receptor binding site.
The switch from a low pathogenic avian influenza (LPAI) phenotype, common in wild birds and poultry, to the HPAI phenotype is achieved by the introduction of basic amino acid
residues into the HA0 cleavage site (5).
992), including 1 change in the HA cleavage site, resulting in a unique arginine (R) > lysine (K) replacement, which contains 6 basic amino acid
residues KRRKKR, whereas all Thai isolates from 2003 and 2004 have RRRKKR.
Although the cleavage site adjacent to the fusion peptide is typically a basic amino acid
, the reported Angrem52 cDNA sequence has an acidic glutamic acid at this position (Figure 1B).
Hu444 is likely not pathogenic in chickens, which is consistent with previous observations that a basic amino acid
at -4 is required for cleavage (5).