• 1
    Costa, T. & Herz, A. (1989) Antagonists with negative intrinsic activity at delta opioid receptors coupled to GTP-binding proteins. Proc. Natl Acad. Sci. USA 86, 73217325.
  • 2
    Lefkowitz, R., Cotecchia, S., Samama, P. & Costa, T. (1993) Constitutive activity of receptors coupled to guanine nucleotide regulatory proteins. Trends Pharmacol. Sci. 14, 303307.
  • 3
    Robinson, P., Cohen, G., Zhukovsky, E. & Oprian, D. (1992) Constitutive active mutants of rhodopsin. Neuron 9, 719725.
  • 4
    Leurs, R., Smit, M., Alewijnse, A. & Timmerman, H. (1998) Agonist-independent regulation of constitutively active G-protein-couple receptors. Trends Biochem. Sci. 23, 418422.
  • 5
    Sadee, W., Hoeg, E., Lucas, J. & Wang, D. (2001) Genetic variations in human G protein-coupled receptors: implications for drug therapy. AAPS Pharmsci. 3, E22.
  • 6
    Takeuchi, S. & Takahashi, S. (1998) Melanocortin receptor genes in the chicken – tissue distributions. Gen. Comp. Endocrinol. 112, 220231.
  • 7
    Takeuchi, S., Teshigawara, K. & Takahashi, S. (2000) Widespread expression of Agouti-related protein (AGRP) in the chicken: a possible involvement of AGRP in regulating peripheral melanocortin systems in the chicken. Biochim. Biophys. Acta 1496, 261269.
  • 8
    Schiöth, H.B. (2001) The physiological role of melanocortin receptors. Vitamin Hormones 63, 195232.
  • 9
    Takeuchi, S., Teshigawara, K. & Takahashi, S. (1999) Molecular cloning and characterization of the chicken pro-opiomelanocortin (POMC) gene. Biochim. Biophys. Acta 1450, 452459.
  • 10
    Slominski, A., Wortsman, J., Luger, T., Paus, R. & Solomon, S. (2000) Corticotropin releasing hormone and proopiomelanocortin involvement in the cutaneous response to stress. Physiol. Rev. 80, 9791020.
  • 11
    Jackson, I. (1997) Homologous pigmentation mutations in human, mouse and other model organisms. Hum. Mol. Genet. 6, 16131624.
  • 12
    Bultman, S., Michaud, E. & Woychik, R. (1992) Molecular characterization of the mouse agouti locus. Cell 71, 11951204.
  • 13
    Robbins, L., Nadeau, J., Johnson, K., Kelly, M., Roselli-Rehfuss, L., Baack, E., Mountjoy, K. & Cone, R. (1993) Pigmentation phenotypes of variant extension locus alleles results from point mutations that alter MSH function. Cell 72, 827834.
  • 14
    Yaswen, L., Diehl, N., Brennan, M. & Hochgeschwender, U. (1999) Obesity in the mouse model of pro-opiomelanocortin deficiency responds to peripheral melanocortin. Nature Med. 5, 10661070.
  • 15
    Våge, D., Lu, D., Klungland, H., Lien, S., Adalsteinsson, S. & Cone, R. (1997) A non-epistatic interaction of the agouti and extension in the fox, Vulpes vulpes. Nature Genet. 15, 311315.
  • 16
    Lu, D., Våge, D. & Roger, D. (1998) A ligand-mimetic model for constitutive activation of the melanocortin-1 receptor. Mol. Endocrinol. 12, 592604.
  • 17
    Valverde, P., Healy, E., Jackson, I., Rees, J.L. & Thody, A.J. (1995) Variants of the melanocyte-stimulating hormone receptor gene are associated with red hair and fair skin in humans. Nature Genet. 11, 328330.
  • 18
    Schiöth, H., Philips, S., Rudzish, R., Birch-Machin, M., Wikberg, J. & Rees, J. (1999) Loss of function mutations of the human melanocortin 1 receptor are common and are associated with red hair. Biochem. Biophys. Res. Commun. 260, 488491.
  • 19
    Rees, J.L., Birch-Machin, M., Flanagan, N., Healy, E., Phillips, S. & Todd, C. (1999) Genetic studies of the human melanocortin-1 receptor. Ann. NY Acad. Sci. 885, 134142.
  • 20
    Takeuchi, S., Suzuki, H., Yabuuchi, M. & Takahashi, S. (1996) A possible involvement of melanocortin 1-receptor in regulating feather color pigmentation in the chicken. Biochim. Biophy Acta 1308, 164168.
  • 21
    Theron, E., Hawkins, K., Bermingham, E., Ricklefs, R. & Mundy, N. (2001) The molecular basis of an avian plumage polymorphism in the wild: a melanocortin-1-receptor point mutation is perfectly associated with the melanic plumage morph of the bananaquit, Coerebra flaveola. Curr. Biol. 11, 120.
  • 22
    Marklund, U., Bystrom, M., Gedda, K., Larefalk, A., Juneblad, K., Nystrom, S. & Ekstrand, A.J. (2002) Intron-mediated expression of the human neuropeptide YY (1) receptor. Mol. Cell Endocrinol. 188, 8597.
  • 23
    Chhajlani, V. & Wikberg, J. (1992) Molecular cloning and expression of the human melanocyte stimulating hormone receptor cDNA. FEBS Lett. 309, 417420.
  • 24
    Gantz, I., Konda, Y., Tashiro, T., Shimoto, Y., Miwa, H., Munzert, G., De Watson, S.J.I., Valle, J. & Yamada, T. (1993) Molecular cloning of a novel melanocortin receptor. J. Biol. Chem. 268, 82468250.
  • 25
    Sazanov, A., Masabanda, J., Eward, D., Takeuchi, S., Tixier-Boichard, M., Buitkamp, J. & Fries, R. (1998) Evolutionarily conseved telomeric localization of BBC1 and MC1R on a microchromosome questions the identity of MC1R and a pigmentation locus on chromosome 1 in chicken. Chromosome Res. 6, 651654.
  • 26
    Okimoto, R., Ellet, A.E. & Takeuchi, S. (2000) Melanocortin 1-receptor (MC1-R.) gene polymorphisms associated with chicken E locus alleles. Poultry Sci. 79, 9.
  • 27
    Våge, D., Klungland, H., Lu, D. & Cone, R. (1999) Molecular and pharmacological characterization of dominant black coat color in sheep. Mamm. Genome 10, 3943.
  • 28
    Frandberg, P.A., Doufexis, M., Kapas, S. & Chhajlani, V. (2001) Cysteine residues are involved in structure and function of melanocortin 1 receptor: Substitution of a cysteine residue in transmembrane segment two converts an agonist to antagonist. Biochem. Biophys. Res. Commun. 281, 851857.
  • 29
    Schiöth, H., Yook, P., Muceniec, R., Wikberg, J. & Szardenings, M. (1998) Chimeric melanocortin MC1 and MC3 receptors: Identification of domains participating in binding of melanocyte-stimulating hormone peptides. Mol. Pharmacol. 54, 154161.
  • 30
    Vaisse, C., Clement, K., Durand, E., Hercberg, S., Guy-Grand, B. & Froguel, P. (2000) Melanocortin-4 receptor mutations are a frequent and heterogeneous cause of morbid obesity. J. Clin. Invest. 106, 253262.
  • 31
    Hinney, A., Schmidt, A., Nottebom, K., Heibult, O., Becker, I., Ziegler, A., Gerber, G., Sina, M., Gorg, T., Mayer, H., Siegfried, W., Fichter, M., Remschmidt, H. & Hebebrand, J. (1999) Several mutations in the melanocortin-4 receptor gene including a nonsense and a frameshift mutation associated with dominantly inherited obesity in humans. J. Clin. Endocrinol. Metab. 84, 14831486.
  • 32
    Benton, M.J. (1993) The Fossil Record 2, 2nd edn. Chapman & Hall, London, UK.
  • 33
    Ringholm, A., Fredriksson, R., Poliakova, N., Yan, Y.L., Postlethwait, J.H., Larhammar, D. & Schioth, H.B. (2002) One melanocortin 4 and two melanocortin 5 receptors from zebrafish show remarkable conservation in structure and pharmacology. J. Neurochem. 82, 618.
  • 34
    Hartl, D.L. & Clark, A.G. (1997) Principles of Population Genetics, 3rd edn. Sinauer, Sunderland, MA, USA.