Fig. 2. Genomic organization of lepidopteran OBPs. (A) Sequence map of clone M2-1S, containing both gobp2Msex and pbp1Msex. Numbers indicate the upstream and downstream bases demarking translational initiation sites (2393, 6626), termination codons (3832, 7795), polyadenylation signals (gobp2Msex, AGTAAA, bp 3885; pbp1Msex, AATAAA, bp 8373) and boundaries between exons (heavy bars) and introns. Restriction sites relevant to Fig. 1 are indicated. The full-length sequence of M2-1S is available from GenBank (accession number AF323972). (B) Size comparison of exons and introns of OBPs. Exon/intron organization within coding regions are compared between GOBP2Msex and PBP1Msex, PBPs of several other moth species, and six OBPs of Drosophila melanogaster. Exon/intron boundaries were determined by comparing derived amino acid sequences with translated genomic DNA sequences. Genomic sequences are represented by large filled boxes (exons), joined by thin lines (introns); lengths are proportional to the scale bar. The 5' ends correspond to the start ATGs and the 3' ends correspond to the termination codons. Genes, taxa and GenBank accession numbers are: MsexG2 (M. sexta GOBP2, AF323972), Msex PBP1 (M. sexta PBP1, AF323972); AperPBP (Antheraea pernyi PBP1, X57562); AvelPBP (Argyrotaenia velutinana AvelE PBP, AF177641); CmurPBP (Choristinoneura murinana Cmur4 PBP, AF177662); CpinPBP (Choristinoneura pinus Cpin4 PBP; AF177653); CrosPBP (Choristinoneura rosaceana CrosC PBP; AF177654); OnubPBP (Ostrinia nubilalis UZ4 PBP, AF133643). PgosPBP (Pectinophora gossypiella PBP, AF177656) DmelOSE, DmelOS-F, DmelPBRP1 DmelPBRP2, DmelPBRP5 DmelLUSH – Drosophila melanogaster OS-E (AE003601); OS-F (PBPRP3) (AE003601); PBPRP1 (AE003541); PBPRP2 (AE003571); PBPRP5 (AE003617); LUSH (AE003516). (Krieger et al., 1991; Pikielny et al., 1994; McKenna et al., 1994; Hekmat-Scafe et al., 1997; Willett and Harrison, 1999; Willett, 2000). (C) Comparison of exon boundaries in OBP proteins. Amino acid alignments of OBP proteins in Fig. 4 are shown. The alignment is limited to regions surrounding the lepidopteran exon boundaries. Sequences were aligned using Clustal X (Thompson et al., 1994). Three of six conserved cysteine residues are marked (X). Intron/exon boundaries of the PBPs and GOBP2 are indicated by numbers (1,2); boundaries in the Drosophila proteins (Dmel) are indicated by letters (A–D). The C-terminal amino acids of exon domains are enclosed by boxes.