Fig. 8.
Phylogenetic relationships of Trp and GPCRs in sea urchins, other invertebrates and vertebrates. A Phylogenetic tree of TrpA and TrpV family receptors. Invertebrate and vertebrate species contained a single TrpA gene that formed a monophyletic clade (a). Invertebrate TrpV orthologs fell into 2 families, one that contained the worm (C. elegans) OSM-9, fruitfly (D. melanogaster) inactive (b), while the other contained the family of worm OCR proteins, fruitfly nanchung, and sea squirt nanLIKE (c). Vertebrate TrpV orthologs also fell into two families, the epithelial calcium channels (ECaC; TrpV5-6) (d) and the TrpV1-like channels (TrpV1-4) (e). Profile HMM searches against the sea urchin genome, with multiple sequence alignments (MSA) containing vertebrate TrpV family members as the query, indicated that the closest similarity between vertebrate and invertebrate TrpV subunits was between the vertebrate epithelial calcium channels (ECaC; TrpV5-6) (d) and the invertebrate sea urchin (S. purpuratus) GLEAN3 06793 in the OCR and nanchung clade (c). GLEAN3 09599 was also identified as a homolog to the vertebrate TrpV proteins in the profile HMM searches, with E-values of 1.0−7 and 1.8−3 in the TrpV5-6 and TrpV1-4 searches, respectively. The TrpA1 ortholog in sea urchins, GLEAN3 15403, had E-values higher than 1.5−4 in the two HMM searches. B Phylogenetic tree of GPCRs. Cannabinoid, Edg-like lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) receptors were found only in vertebrates and the urochordates sea squirt (C. intestinalis) and Pacific sea human and fruitfly D1-5 dopamine receptors formed a clade with multiple sea urchin GLEAN3 sequences, including the adrenergic-like GLEAN3 21588 and D1-like GLEAN3 11320 (h). HMM searches against the sea urchin genome including all currently identified GPCR receptors, using the urochordate and cephalochordate CB receptors as query, identified the sea urchin GLEAN3 21588 as the most similar. HMM searches with vertebrate CB sequences also included in the search alignment identified the D1-like GLEAN3 11320 as the most similar. All other GLEAN3 GPCR receptors in the phylogenetic tree had bit scores lower than −55.5 and E-values higher than 3.0−7 for the first HMM search containing only the urochordate and cephalochordate sequences. In the search also including vertebrate CB receptors, all other GLEAN3 GPCR receptors in the phylogenetic tree had bit scores lower than −43.1 and E-values higher than 1.5−10.