9PMT | pdb_00009pmt

Structure of an anti-VHH fab fragment bound to nanobody Nb33


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.26 Å
  • R-Value Free: 
    0.244 (Depositor), 0.244 (DCC) 
  • R-Value Work: 
    0.203 (Depositor), 0.202 (DCC) 
  • R-Value Observed: 
    0.205 (Depositor) 

wwPDB Validation 3D Report Full Report

Validation slider image for 9PMT

This is version 1.1 of the entry. See complete history

Literature

Hypervariable loop profiling decodes sequence determinants of antibody stability.

Wan, Y.Liang, J.Dai, Y.Srinivasan, K.Billesbolle, C.Zhu, J.F.Shin, J.E.Paul, S.Marks, D.Song, Y.S.Myers, B.R.Koehl, A.Manglik, A.

(2026) Nat Struct Mol Biol 

  • DOI: https://doi.org/10.1038/s41594-026-01804-9
  • Primary Citation Related Structures: 
    9PMT

  • PubMed Abstract: 

    Antibody folding and aggregation are major challenges in the development of relevant reagents and therapeutics. Antibodies face a biophysical trade-off; the immense diversity in complementarity-determining regions (CDRs), which is crucial for broad antigen recognition, comes at the cost of folding stability. How CDR sequences influence antibody folding remains poorly understood because of their sequence diversity and lack of large-scale data. Here we develop a high-throughput 'deep loop profiling' approach to quantify folding fitness across millions of diverse CDRs. Machine learning models trained on this dataset predict folding propensity directly from sequence and identify interpretable residue-level rules that reveal CDR1 and CDR2 as key folding determinants. Using these insights, we rescue two unstable nanobodies, including an aggregation-prone SARS-CoV-2 binder and a G-protein-coupled receptor-targeting intrabody, and build next-generation synthetic libraries enriched for biophysically optimized nanobodies. This approach provides a scalable framework for understanding and engineering folding competence in antibody-based scaffolds.


  • Organizational Affiliation
    • Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA.

Macromolecule Content 

  • Total Structure Weight: 64.99 kDa 
  • Atom Count: 4,272 
  • Modeled Residue Count: 552 
  • Deposited Residue Count: 606 
  • Unique protein chains: 3

Macromolecules

Find similar proteins by:|  3D Structure
Entity ID: 1
MoleculeChains  Sequence LengthOrganismDetailsImage
Anti-VHH fab Heavy ChainA [auth H]236Oryctolagus cuniculusMutation(s): 0 
Find similar proteins by:|  3D Structure
Entity ID: 2
MoleculeChains  Sequence LengthOrganismDetailsImage
Anti-VHH fab Light ChainB [auth L]234Oryctolagus cuniculusMutation(s): 0 
Find similar proteins by:|  3D Structure
Entity ID: 3
MoleculeChains  Sequence LengthOrganismDetailsImage
Nanobody Nb33C [auth N]136Lama glamaMutation(s): 0 

Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.26 Å
  • R-Value Free:  0.244 (Depositor), 0.244 (DCC) 
  • R-Value Work:  0.203 (Depositor), 0.202 (DCC) 
  • R-Value Observed: 0.205 (Depositor) 
Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 64.551α = 90
b = 66.785β = 90
c = 141.608γ = 90
Software Package:
Software NamePurpose
PHENIXrefinement
Aimlessdata scaling
XDSdata reduction
PHASERphasing
PDB_EXTRACTdata extraction

Structure Validation

View Full Validation Report



Entry History 

& Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute on Drug Abuse (NIH/NIDA)United States3R01DA010711-22S1

Revision History  (Full details and data files)

  • Version 1.0: 2026-05-06
    Type: Initial release
  • Version 1.1: 2026-05-20
    Changes: Database references