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G-protein coupled receptor chimera

        - use of chimera mGlu1/mGlu5 and CaR/mGlu showed that the pharmacological specificity of these agents depends on aa in TM domain, i.e. Thr815 and Ala818 in TM VII of mGlu1 are essential for antagonist activity of CPCCOEt [Litschig, S., F. Gasparini, D. Rueegg, N. Stoehr, P.J. Flor, I. Vranesic, L. Prezeau, J.P. Pin, C. Thomsen, and R. Kuhn, CPCCOEt, a noncompetitive metabotropic glutamate receptor 1 antagonist, inhibits receptor signaling without affecting glutamate binding. Mol Pharmacol, 1999. 55(3): p. 453-61.]

    - there seems to be a lack of specificity in activation of TM domain of mGluR: chimera mGlu1(1-592)/CaR(613-1078) was able to be activated by glutamate [Hammerland, L.G., K.J. Krapcho, J.E. Garrett, N. Alasti, B.C. Hung, R.T. Simin, C. Levinthal, E.F. Nemeth, and F.H. Fuller, Domains determining ligand specificity for Ca2+ receptors. Mol Pharmacol, 1999. 55(4): p. 642-8]


chimeric receptors are supposed to show that the receptor activation mechanism lies within the TM domain, where most conserved residues are located

"extra- or intracellular loops and termini can be exchanged between different receptors, leaving intact the receptor's capacity to be activated, while swapping ligand or G protein specificity" Gerber et al

some chimeric work is reviewed in Bourne (1997) How receptors talk to trimeric G proteins. Curr. Opin. Cell Biol. 9, 134-142. (refs. 44 and 45)


- chimera alpha2/beta2 adrenergic receptors and muscarinic M2/M5 receptors used for identification of helix I&VII close proximity, reviewed in Gether (2000):

        Suryanarayana, S., M. von Zastrow, and B.K. Kobilka, Identification of intramolecular interactions in adrenergic receptors. J Biol Chem, 1992. 267(31): p. 21991-4.

        Pittel, Z. and J. Wess, Intramolecular interactions in muscarinic acetylcholine receptors studied with chimeric m2/m5 receptors. Mol Pharmacol, 1994. 45(1): p. 61-4.

        Liu, J., T. Schoneberg, M. van Rhee, and J. Wess, Mutational analysis of the relative orientation of transmembrane helices I and VII in G protein-coupled receptors. J Biol Chem, 1995. 270(33): p. 19532-9.

        Mizobe, T., M. Maze, V. Lam, S. Suryanarayana, and B.K. Kobilka, Arrangement of transmembrane domains in adrenergic receptors. Similarity to bacteriorhodopsin. J Biol Chem, 1996. 271(5): p. 2387-9.


- Tachykinin nonpetide antagoinists: using chimera NK-1/NK-3 receptors show that CP96,345 binds differently from substance P (several chimeric exchanges that dramatically affect CP96,345 did not affect substance P), ref. Gether, U., T.E. Johansen, R.M. Snider, J.A. Lowe, 3rd, S. Nakanishi, and T.W. Schwartz, Different binding epitopes on the NK1 receptor for substance P and non-peptide antagonist. Nature, 1993. 362(6418): p. 345-8


-- chimera between E-II in beta2/alpha1B-adrenergic receptor is constitutively active  (See Gether 2000 review) 

- using chimeric LH/FSH receptors it was shown that stabilizing interaction between TM V and VI are important for resistance of FSH receptor to constitutively activating mutation (see Gether 2000 review)