Analysis of Penaeus monodon Saposin (PmSap) . (A) The full-length cDNA and deduced protein sequence of PmSap (3034 bp; ORF 2589 bp, 862 aa) of P. monodon. Start (ATG) and stop (TAA) codons are illustrated in boldface and underlined. The signal peptide of the deduced PmSap protein is italicized and underlined. Putative N-linked glycosylation sites are underlined. Two domains of Saposin A (positions 25-58 and 823-856) and seven domains Saposin B (positions 68-144, 178-251, 272-346, 437-512, 531-606, 646-721, and 738-813 of the deduced protein) are highlighted. (B) Diagram showing SapA and SapB domains in prosaposin in various vertebrates; Homo sapiens (CAI40836), Bos taurus (NP_776586), Macaca mulatta (XP_001106592), Canis familiaris (XP_536382 and XP_861441), Gallus gallus (NP_990142), Danio rerio (AAH63994) and saposin-related protein in invertebrates; Acyrthosiphon pisum (XP_001943244), Apis mellifera (XP_392338), Tribolium castaneum (XP_966852), Aedes aegypti (XP_001662994), Culex quinquefasciatus (XP_001864689), Drosophila melanogaster (NP_524597 and NP_733408), Drosophila simulans (XP_002105562), Nasonia vitripennis (XP_001603446) and Ixodes scapularis (XP_002412058). Sequenced were retrieved from the GenBank and compared with saposin-related protein of P. monodon. Four SapB domains are conserved in vertebrate saposins whereas the number of SapB domains varies among invertebrate taxa.