Core protein, Tick-borne encephalitis virus (C protein)

Tick-borne encephalitis virus (TBEV) has a single positive-stranded RNA genome, about 11kb long (10,405–11,103 nucleotides), with an open reading frame (ORF) encoding a polyprotein, which is cleaved into three structural proteins (C, M, and E) and seven non-structural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5) after co- and post-translational protease processing. The C protein is the smallest structural protein containing approximately 100 amino acid residues. Despite its small size, C protein carries an extremely high positive charge due to the high content of basic amino acids. Hence, the isoelectric point of this protein is around 12. Based on this feature, the C protein is considered to be a member of the so-called supercharged proteins.