Human folate receptor alpha (FOLR1) at acidic pH, triclinic form

Experimental Data Snapshot

  • Resolution: 1.80 Å
  • R-Value Free: 0.269 
  • R-Value Work: 0.222 
  • R-Value Observed: 0.224 

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This is version 1.3 of the entry. See complete history


Structures of human folate receptors reveal biological trafficking states and diversity in folate and antifolate recognition.

Wibowo, A.S.Singh, M.Reeder, K.M.Carter, J.J.Kovach, A.R.Meng, W.Ratnam, M.Zhang, F.Dann, C.E.

(2013) Proc Natl Acad Sci U S A 110: 15180-15188

  • DOI: https://doi.org/10.1073/pnas.1308827110
  • Primary Citation of Related Structures:  
    4KM6, 4KM7, 4KMX, 4KMY, 4KMZ, 4KN0, 4KN1, 4KN2

  • PubMed Abstract: 

    Antifolates, folate analogs that inhibit vitamin B9 (folic acid)-using cellular enzymes, have been used over several decades for the treatment of cancer and inflammatory diseases. Cellular uptake of the antifolates in clinical use occurs primarily via widely expressed facilitative membrane transporters. More recently, human folate receptors (FRs), high affinity receptors that transport folate via endocytosis, have been proposed as targets for the specific delivery of new classes of antifolates or folate conjugates to tumors or sites of inflammation. The development of specific, FR-targeted antifolates would be accelerated if additional biophysical data, particularly structural models of the receptors, were available. Here we describe six distinct crystallographic models that provide insight into biological trafficking of FRs and distinct binding modes of folate and antifolates to these receptors. From comparison of the structures, we delineate discrete structural conformations representative of key stages in the endocytic trafficking of FRs and propose models for pH-dependent conformational changes. Additionally, we describe the molecular details of human FR in complex with three clinically prevalent antifolates, pemetrexed (also Alimta), aminopterin, and methotrexate. On the whole, our data form the basis for rapid design and implementation of unique, FR-targeted, folate-based drugs for the treatment of cancer and inflammatory diseases.

  • Organizational Affiliation

    Department of Chemistry, Indiana University, Bloomington, IN 47405.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Folate receptor alpha
A, B
207Homo sapiensMutation(s): 0 
Gene Names: FOLR1
UniProt & NIH Common Fund Data Resources
Find proteins for P15328 (Homo sapiens)
Explore P15328 
Go to UniProtKB:  P15328
PHAROS:  P15328
GTEx:  ENSG00000110195 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP15328
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.80 Å
  • R-Value Free: 0.269 
  • R-Value Work: 0.222 
  • R-Value Observed: 0.224 
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 33.709α = 72.23
b = 55.384β = 86.95
c = 69.504γ = 90.12
Software Package:
Software NamePurpose
SCALEPACKdata scaling
PDB_EXTRACTdata extraction
HKL-2000data collection
DENZOdata reduction

Structure Validation

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Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2013-08-07
    Type: Initial release
  • Version 1.1: 2013-10-02
    Changes: Database references
  • Version 1.2: 2017-11-15
    Changes: Refinement description
  • Version 1.3: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Advisory, Data collection, Derived calculations, Structure summary