Neighbor-joining phylogenetic trees for the Family A, Group III-B receptors. For Family and Group classifications, see Kolakowski (1994) (see http://www.gcrdb.uthscsa.edu/). (A) Rooted tree for the gastrin/cholecystokinin (CCK) receptors. (B) Unrooted tree for the neurokinin receptors (NKRs) and related GPCRs. The midpoint of the tree is indicated with an “X.” (C)Unrooted tree for the neuropeptide Y (NPY) receptors (NPYRs) and prolactin releasing receptors (PRPRs). (D) Rooted tree for the bombesin/gastrin releasing peptide receptors. (E) Unrooted tree for the neuromedin U receptors (NMURs), growth hormone secretagogue receptors (GHSRs), neurotensin receptors (NTRs), thyrotropin releasing hormone receptors (TRFRs), and a large family of related orphan receptors from Caenorhabditis elegans. The C. elegans orphan receptors included here belong to one of three clades (classes A–C). (*) Omitted receptors are additional C. elegansorphan GPCRs; (**) omitted receptors are additional GHSRs and closely related orphan GPCRs. In A and D, a monophyletic set of 26 biogenic amine receptors (not shown) was used as the outgroup to determine the root of the trees (see Methods). In C andE, the location of the tree midpoint was ambiguous and is therefore not indicated. Portions of the trees representing groups of closely related receptors were omitted (the number of related receptors on each branch is indicated in parentheses). Drosophila GPCRs are listed in bold and italics. (BRS3) Bombesin receptor subtype 3; (BRS4) bombesin receptor subtype 4; (CCKR) CCK receptor type A; (CCKR XL) Xenopus laevis CCKR; (GASR) gastrin/CCK receptor type B; (GCRC) glucocorticoid-induced receptor; (GRL106) Lymnaea stagnalis cardioexcitatory receptor; (GRPR) gastrin releasing peptide (GRP) receptor; (LKR) Boophilus microplus (tick) leucokinin-like peptide receptor; (LSR) L. stagnalislymnokinin receptor; (NFFR) neuropeptide FF/neuropeptide AF receptor; (NK1R–NK3R) NKR types 1–3; (NMU1R and NMU2R) neuromedin U receptor types 1 and 2; (NPR-1) product of the C. elegans npr-1 gene; (NPYRYA–NPYRYC) orphan zebrafish NPYRs; (NPYRB) Gadus morhua(Atlantic cod) NPYR; (NTR1 and NTR2) neurotensin receptor types 1 and 2; (NY1R–NY6R) NPY receptor types 1–6; (OT7T022) putative mammalian RFRP receptor; (OXR) orexin/hypocretin receptor; (STKR) Stomoxys calcitrans (stable fly) tachykinin receptor. The remaining non-Drosophila sequences are orphan GPCRs from C. elegans. Symbols denote bootstrap support, out of 1000 replicates, that was >500: (filled circles) >990; (open circles) >900; (open squares) >700; (open triangles) >500.
