Crystal structure of the Mer kinase domain in complex with a macrocyclic inhibitor

Experimental Data Snapshot

  • Resolution: 2.10 Å
  • R-Value Free: 0.257 
  • R-Value Work: 0.211 
  • R-Value Observed: 0.214 

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The Axl kinase domain in complex with a macrocyclic inhibitor offers first structural insights into an active TAM receptor kinase.

Gajiwala, K.S.Grodsky, N.Bolanos, B.Feng, J.Ferre, R.Timofeevski, S.Xu, M.Murray, B.W.Johnson, T.W.Stewart, A.

(2017) J Biol Chem 292: 15705-15716

  • DOI: https://doi.org/10.1074/jbc.M116.771485
  • Primary Citation of Related Structures:  
    5U6B, 5U6C

  • PubMed Abstract: 

    The receptor tyrosine kinase family consisting of Tyro3, Axl, and Mer (TAM) is one of the most recently identified receptor tyrosine kinase families. TAM receptors are up-regulated postnatally and maintained at high levels in adults. They all play an important role in immunity, but Axl has also been implicated in cancer and therefore is a target in the discovery and development of novel therapeutics. However, of the three members of the TAM family, the Axl kinase domain is the only one that has so far eluded structure determination. To this end, using differential scanning fluorimetry and hydrogen-deuterium exchange mass spectrometry, we show here that a lower stability and greater dynamic nature of the Axl kinase domain may account for its poor crystallizability. We present the first structural characterization of the Axl kinase domain in complex with a small-molecule macrocyclic inhibitor. The Axl crystal structure revealed two distinct conformational states of the enzyme, providing a first glimpse of what an active TAM receptor kinase may look like and suggesting a potential role for the juxtamembrane region in enzyme activity. We noted that the ATP/inhibitor-binding sites of the TAM members closely resemble each other, posing a challenge for the design of a selective inhibitor. We propose that the differences in the conformational dynamics among the TAM family members could potentially be exploited to achieve inhibitor selectivity for targeted receptors.

  • Organizational Affiliation

    From Oncology Medicinal Chemistry and ketan.gajiwala@pfizer.com.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Tyrosine-protein kinase Mer
A, B
315Homo sapiensMutation(s): 0 
Gene Names: MERTKMER
UniProt & NIH Common Fund Data Resources
Find proteins for Q12866 (Homo sapiens)
Explore Q12866 
Go to UniProtKB:  Q12866
GTEx:  ENSG00000153208 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ12866
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on 7YS

Download Ideal Coordinates CCD File 
C [auth A],
D [auth B]
C21 H22 Cl F N6 O3
Binding Affinity Annotations 
IDSourceBinding Affinity
7YS Binding MOAD:  5U6C Ki: 0.05 (nM) from 1 assay(s)
Experimental Data & Validation

Experimental Data

  • Resolution: 2.10 Å
  • R-Value Free: 0.257 
  • R-Value Work: 0.211 
  • R-Value Observed: 0.214 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 51.692α = 90
b = 92.33β = 100.8
c = 69.269γ = 90
Software Package:
Software NamePurpose
XDSdata reduction
SCALAdata scaling

Structure Validation

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Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2017-07-26
    Type: Initial release
  • Version 1.1: 2017-08-02
    Changes: Database references
  • Version 1.2: 2017-10-04
    Changes: Database references
  • Version 1.3: 2023-10-04
    Changes: Data collection, Database references, Refinement description