Amino acid sequences of M. sexta PGRP1 (Ms1, AF413068), T. ni PGRP (Tn, AAC31820), B. mori PGRP (Bm1, BAA77209), S. cynthia PGRP-A (ScA, BAF03522), D. melanogaster PGRP-SA (DmSA, NP_572727), -LC (DmLC, NP_729468.2), -LE (DmLE, NP_573078), H. sapiens PGRP-IαC (HsIαC, AAK72484), and T7 lysozyme (T7, NP_0419731) are aligned. Residue numbers of mature M. sexta PGRP1 are indicated on top of its sequence. Identical and similar residues in PGRPs are marked with “*” and “:”, respectively. Residues corresponding to Asn236 and Phe237 of human PGRP-IαC and Arg254 of Drosophila PGRP-LE are shown in bold. The muramyl tripeptide-interacting residues in human PGRP-IαC are shaded gray, residues identical in the lepidopteran PGRPs are highlighted, and residues for Zn2+-binding and amidase activity in T7 lysozyme are double underlined.