Fig. 5

a Domain composition of Crumbs proteins of D. melanogaster (Dcrb), M. musculus (CRB1, CRB2), O. lobularis, S. ciliatum, A. queenslandica, O. minuta, N. vectensis and T. adhaerens. Domains are shown as detected by SMART and Pfam and scaled with IBS software. Crumbs transmembrane proteins consist of extracellular epidermal growth factor (EGF), laminin-like (LAM) repeats and a short cytoplasmic domain. No crumbs was detected in Ctenophora. In contrast to other animals, sponges have only one copy of Crumbs. b Alignment of the cytoplasmic domain of Crumbs that binds PALS1 and PAR6. Transmembrane and intracellular domains were aligned with MAFFT v7.123b and displayed with JalView. The transmembrane domain, the FERM binding domains (FBM) containing the RxxxGxYxPS motif needed for the interaction with the Ezrin-Radixin-Moesin (ERM) protein family, the Proline rich domain and the PDZ binding domain (PDZ-BD) are depicted at the bottom. The FBM presents a different conservation depending on the sponge class considered (from 2 to 5 conserved residues). Asterisks indicate the position of the two phosphorylation sites recognized by aPKC. These sites are absent in placozoans and poriferans. The PDZ-BD domain (interacting with MPP5) is well-conserved in non bilaterians except in glass sponges