RXFP1 Couples to the Gαi3-Gβγ-PI3K-PKCζ Pathway via the Final 10 Amino Acids of the Receptor C-terminal Tail

Authors

  • Michelle L. Halls,

    1. Department of Pharmacology, Monash University, Clayton, Victoria 3800, Australia
    2. Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
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  • Maria Papaioannou,

    1. Department of Pharmacology, Monash University, Clayton, Victoria 3800, Australia
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  • John D. Wade,

    1. Howard Florey Institute, University of Melbourne, Parkville, Victoria 3010, Australia
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  • Bronwyn A. Evans,

    1. Department of Pharmacology, Monash University, Clayton, Victoria 3800, Australia
    2. Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
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  • Ross A. D. Bathgate,

    1. Howard Florey Institute, University of Melbourne, Parkville, Victoria 3010, Australia
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  • Roger J. Summers

    1. Department of Pharmacology, Monash University, Clayton, Victoria 3800, Australia
    2. Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
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Address for correspondence: Prof. Roger J. Summers, Department of Pharmacology, P.O. Box 13E, Monash University, Clayton, Victoria 3800, Australia. Voice: +61 3 9905 1440; fax: +61 3 9905 8192. roger.summers@med.monash.edu.au

Abstract

The relaxin family peptide receptors RXFP1 and RXFP2 are highly similar receptors that share approximately 80% amino acid sequence homology. Constitutively active receptors couple to increased cAMP accumulation, which is important for relaxin-mediated decidualization and myometrial inhibition. Despite the high homology, the receptors couple to different G-proteins to affect cAMP accumulation. This study aimed to determine the region of RXFP1 that directs coupling to the delayed Gαi3 pathway by using receptor mutagenesis. Receptor chimeras suggested that activation of this pathway by RXFP1 was dependent upon the membrane-anchored domain of the receptor. Further receptor mutagenesis showed that activation of the Gαi3-Gβγ-PI3K-PKCζ cAMP pathway by RXFP1 is dependent upon the C-terminal 10 amino acids of the receptor and absolutely requires Arg752.

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