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Modeling the Primary Hormone-Binding Site of RXFP1 and RXFP2

Authors

  • Daniel J. Scott,

    1. Howard Florey Institute
    2. Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3010, Australia
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  • Geoffrey W. Tregear,

    1. Howard Florey Institute
    2. Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3010, Australia
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  • Ross A. D. Bathgate

    1. Howard Florey Institute
    2. Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3010, Australia
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Address for correspondence: Ross A. D. Bathgate, Howard Florey Institute, University of Melbourne, Victoria 3010, Australia. Voice: +61-3-8344-5648; fax: +61-3-9347-0446. bathgate@florey.edu.au

Abstract

The primary binding sites of the relaxin and insulin-like peptide 3 (INSL3) receptors, RXFP1 and RXFP2, are found within the leucine-rich repeats (LRRs) of the ectodomains. Specific B-chain residues in the peptides interact with residues in the inner β-sheets of the LRRs of the receptors. Relaxin binds to RXFP2 with high affinity, although INSL3 has a very poor affinity for RXFP1. In this paper we present evidence that relaxin binds to the LRRs of RXFP2 in a manner similar to INSL3 binding to its receptor. Additionally, we introduce a model of this binding interaction and compare it to an alternate model for relaxin–RXFP1 binding.

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