9QU3 | pdb_00009qu3

Cryo-EM structure of the human choline transporter-like protein hCTL1 in LMNG

• PDB DOI: https://doi.org/10.2210/pdb9QU3/pdb
• EM Map EMD-50252: EMDB EMDataResource

• Classification: MEMBRANE PROTEIN
• Organism(s): Homo sapiens
• Expression System: Spodoptera frugiperda
• Mutation(s): No 


• Deposited: 2025-04-10 Released: 2025-05-14 
• Deposition Author(s): Driller, J.H., Nel, L., Pedersen, B.P.
• Funding Organization(s): Lundbeckfonden, H2020 Marie Curie Actions of the European Commission, Danish National Research Foundation, The Carlsberg Foundation

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Experimental Data Snapshot

• Method: ELECTRON MICROSCOPY
• Resolution: 3.20 Å
• Aggregation State: PARTICLE 
• Reconstruction Method: SINGLE PARTICLE 

Literature

Structural and biochemical comparison of the FLVCR and CTL membrane protein families in eukaryotes.

Nel, L., Driller, J.H., Driller, R., Frain, K.M., Pedersen, B.P.

(2026) Life Sci Alliance 9

• PubMed: 42114998 
• DOI: https://doi.org/10.26508/lsa.202503583
• Primary Citation Related Structures: 
  9F63, 9QU3, 9QU4


• PubMed Abstract: 
  

  The organic cation choline is essential for eukaryotic metabolism. Recently, the feline leukemia virus subgroup C receptor-related (FLVCR, SLC49) family was demonstrated as central for basal choline transport, questioning the role of the choline transporter-like (CTL, SLC44) family in this capacity. Here, we use Xenopus laevis oocytes to confirm that FLVCR1 (SLC49A1) and FLVCR2 (SLC49A2) proteins are choline transporters. CTL1 (SLC44A1) does not transport choline under the same conditions, supported by other CTL proteins, Arabidopsis thaliana CherI and Saccharomyces cerevisiae PNS1, which also display no choline transport activity. We present the atomic structures of FLVCR2, CTL1, and PNS1. The 3.4 Å cryo-EM structure of FLVCR2 has choline in the binding pocket. The 3.3 Å cryo-EM structure of CTL1 and the 2.7 Å crystal structure of PNS1 reveal an unusual protein fold, weakly related to the mitochondrial carrier family (SLC25). The unusual fold appears incompatible with transmembrane transport and implies a different and, so far, unknown function for CTL proteins. Our results support FLVCR proteins as choline transporters and suggest a nontransport role for CTL proteins.

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Organizational Affiliation: 
• Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.
Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark [e-mail].

Biological Assembly 1  

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 1 assigned by authors and generated by (software)

Biological Assembly Evidence: electron microscopy

Macromolecule Content 

• Total Structure Weight: 73.89 kDa 
• Atom Count: 2,889 
• Modeled Residue Count: 362 
• Deposited Residue Count: 662 
• Unique protein chains: 1

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Choline transporter-like protein 1	A	662	Homo sapiens	Mutation(s): 0  Gene Names: SLC44A1, CD92, CDW92, CTL1
UniProt & NIH Common Fund Data Resources
Find proteins for Q8WWI5 (Homo sapiens) Explore Q8WWI5  Go to UniProtKB:  Q8WWI5
PHAROS:  Q8WWI5 GTEx:  ENSG00000070214

Experimental Data & Validation

Experimental Data

• Method: ELECTRON MICROSCOPY
• Resolution: 3.20 Å
• Aggregation State: PARTICLE 
• Reconstruction Method: SINGLE PARTICLE 

EM Software:

Task	Software Package	Version
MODEL REFINEMENT	PHENIX	1.21.2_5419

Structure Validation

Entry History 

& Funding Information

Deposition Data

• Released Date: 2025-05-14 
Deposition Author(s): Driller, J.H., Nel, L., Pedersen, B.P.

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Funding Organization	Location	Grant Number
Lundbeckfonden	Denmark	R380-2021-1207
H2020 Marie Curie Actions of the European Commission	European Union	890822
Danish National Research Foundation	Denmark	0135-00032B
The Carlsberg Foundation	Denmark	CF19-0127

Revision History  

• Version 1.0: 2025-05-14
  Type: Initial release
  
• Version 1.1: 2026-05-27
  Changes: Database references