Sequence similarity between NS4B carboxy terminal domain and the membrane binding domain of D-lactate dehydrogenase. A. Multiple sequence alignment of the carboxy terminal domain of four genotypes of HCV NS4B proteins and the membrane binding domain of four d-LDH family members (referenced by their accession numbers). Bold residues highlight amino-acids present in both families. Basic residues (R, K, H) making up the potential electropositive surface are indicated (+). Dotted line indicates disordered region in the d-LDH crystal structure. Arrowheads point to mutations made in the CTD of NS4B. B. Ribbon representation of the membrane anchored side of d-LDH (PDB code 1F0X). Stick residues indicate the surface exposed amino-acids of the ordered membrane binding helix.