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Evaluation and extension of the two-site, two-step model for binding and activation of the chemokine receptor CCR1

Sanchez, Julie; e Huma, Zil; Lane, J.Robert; Liu, Xuyu; Bridgford, Jessica Lee; Payne, Richard J.; Canals, Meritxell; Stone, Martin J.


Julie Sanchez

Zil e Huma

Associate Professor

Xuyu Liu

Jessica Lee Bridgford

Richard J. Payne

Martin J. Stone


© 2019 Sanchez et al. Published under exclusive license by The American Society for Biochemistry and Molecular Biology, Inc. Interactions between secreted immune proteins called chemokines and their cognate G protein– coupled receptors regulate the trafficking of leukocytes in inflammatory responses. The two-site, two-step model describes these interactions. It involves initial binding of the chemokine N-loop/3 region to the receptor’s N-terminal region and subsequent insertion of the chemokine N-terminal region into the transmembrane helical bundle of the receptor concurrent with receptor activation. Here, we test aspects of this model with C-C motif chemokine receptor 1 (CCR1) and several chemokine ligands. First, we compared the chemokine-binding affinities of CCR1 with those of peptides corresponding to the CCR1 N-terminal region. Relatively low affinities of the peptides and poor correlations between CCR1 and peptide affinities indicated that other regions of the receptor may contribute to binding affinity. Second, we evaluated the contributions of the two CCR1-interacting regions of the cognate chemokine ligand CCL7 (formerly monocyte chemoattractant protein-3 (MCP-3)) using chimeras between CCL7 and the non-cognate ligand CCL2 (formerly MCP-1). The results revealed that the chemokine N-terminal region contributes significantly to binding affinity but that differences in binding affinity do not completely account for differences in receptor activation. On the basis of these observations, we propose an elaboration of the two-site, two-step model—the “three-step” model—in which initial interactions of the first site result in low-affinity, nonspecific binding; rate-limiting engagement of the second site enables high-affinity, specific binding; and subsequent conformational rearrangement gives rise to receptor activation.


Sanchez, J., e Huma, Z., Lane, J., Liu, X., Bridgford, J. L., Payne, R. J., …Stone, M. J. (2018). Evaluation and extension of the two-site, two-step model for binding and activation of the chemokine receptor CCR1. Journal of Biological Chemistry, 294(10), 3464-3475.

Journal Article Type Article
Acceptance Date Dec 19, 2018
Online Publication Date Dec 19, 2018
Publication Date Dec 19, 2018
Deposit Date Jan 10, 2019
Publicly Available Date Jan 10, 2019
Journal Journal of Biological Chemistry
Print ISSN 0021-9258
Electronic ISSN 1083-351X
Publisher American Society for Biochemistry and Molecular Biology
Peer Reviewed Peer Reviewed
Volume 294
Issue 10
Article Number 006535
Pages 3464-3475
Keywords Cell Biology; Biochemistry; Molecular Biology
Public URL


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