Subdomain-specific distribution of residues conserved in PLP1a and PLP1b/c. The structures shown are tertiary structures of PRRSV-2 PLP1a (A) and PLP1b (B) with residues conserved in all non-WPDV arteriviral PLP1a and PLP1b/PLP1c domains, respectively. The N-terminal subdomain, formed by α-helices, is shown in cyan; and the C-terminal subdomain, consisting of antiparallel β-strands, is shown in blue. Conserved residues are shown in yellow (catalytic dyad) and red (all the rest). The following residues were conserved in the PLP1a alignment and mapped on PRRSV-2 (accession number EU624117.1) nsp1a: left subdomain, Gly45, Cys76, and Gly109; and right subdomain, Pro134, Tyr141, His146, Phe152, Ala155, and Pro175. The following residues were conserved in the PLP1b/c alignment and mapped on PRRSV-2 (accession number EU624117.1) nsp1b: left subdomain, Gly88, Cys90, Trp91, Leu94, Ala110, Gly120, Gly123, Tyr125, and Leu126; and right subdomain, Gly143, His159, Leu160, and Gly203. The figure was prepared with PyMOL (85).