Sequence analysis of Platynereis Trk (PduTrk) and p75 (Pdup75) shows conserved domains. (a) Predicted a.a. sequence of Platynereis Trk, multiple sequence alignment for Platynereis Trk TK intracellular domain. Predicted domains are outlined in different colors in the sequence and represented in the schematic drawing on the right. LRR, green: leucine rich repeats domains, IgG, purple: immunoglobulin domain, light blue: transmembrane domain, and TK, gray: intracellular tyrosine kinase domain. Important signatures are also highlighted in the sequence, numbered in the alignment (1–5), and described more in detail in the text. 1: juxtamembrane domain, Src binding site, 2: ATP binding site, 3: conserved aspartate (D) in the catalytic site, 4: autophosphorylation domain, and 5: binding for PLCγ. (b) Predicted a.a. sequence and multiple sequence alignment for Platynereis p75. Predicted domains: CRD1–4, orange: cysteine rich domains, light blue: transmembrane domain, and DD, gray: intracellular death domain. The alignment shows the extracellular CRD1, CRD2, and CRD4 domains and the intracellular portion, containing also the DD domain. The alignment for the less conserved CRD3 is not shown. In both red labels there is the predicted signal peptide. Pdu: Platynereis dumerilii, Ct: Capitella teleta, Bf: Branchiostoma floridae, Dpulex: Daphnia pulex, h: Homo sapiens, and m: Mus musculus.