Fig. 2

Innate immunity pattern recognition receptors (PRRs) in malacostracans. a Domain architecture of PRRs. The neuronal transmembrane protein of the immunoglobulin (Ig) superfamily DSCAM contains tandem arrays of Ig and fibronectin domains. DSCAM is shown to participate in pathogen recognition in mosquitoes and phagocytosis flies. Scavenger receptors are a diverse group of multidomain proteins. Two classes of the membrane-associated scavenger receptors are shown. Members of the class A scavenger receptors (SCRAs) subfamily contain the characteristic scavenger receptor cysteine-rich (SRCR) domain, C-type lectin and collagenous domains. Class B scavenger receptors (SCRBs) are characterised by two transmembrane domains and a CD36 domain. PGRP-LC contains the RHIM (receptor-interacting protein homotypic interaction motif) domain. GNBPs typically possess the β-glucan binding domain and the β-glucanase domain. Domeless is a cytokine receptor required for JAK-STAT signalling. Conserved protein domains of PRRs are shown in the figure inset. Phylogenetic trees of b DSCAM, c Domeless and d Galectin are constructed using the maximum-likelihood method from an amino acid multiple sequence alignment. Taxa labels are depicted as their respective colour codes. Bootstrap support values (n = 1000) for all trees can be found in Additional file 26: Figure S14. Scale bar represents substitution per site. e The graphs represent the repertoire of putative PRR transcripts of the following gene families: SCRAs and SCRBs, GNBPs and C-type lectins. The y-axes represent total number of genes identified in all 55 malacostracan species for each family. Each species is represented by a number on the X-axes and a complete list of species is available in Additional file 3:Table S2. Black horizontal bars below each graph delimit the five orders of malacostracans and the numbers in parentheses (x/y) represent the following: x = number of species in which a particular gene family is found and y = total number of species in each order