Human serum albumin mutant r218p complexed with thyroxine (3,3',5,5'-tetraiodo-l-thyronine)

Experimental Data Snapshot

  • Resolution: 2.80 Å
  • R-Value Free: 0.245 
  • R-Value Work: 0.203 
  • R-Value Observed: 0.203 

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Structural Basis of Albumin-Thyroxine Interactions and Familial Dysalbuminemic Hyperthyroxinemia

Petitpas, I.Petersen, C.E.Ha, C.E.Bhattacharya, A.A.Zunszain, P.A.Ghuman, J.Bhagavan, N.V.Curry, S.

(2003) Proc Natl Acad Sci U S A 100: 6440

  • DOI: https://doi.org/10.1073/pnas.1137188100
  • Primary Citation of Related Structures:  
    1HK1, 1HK2, 1HK3, 1HK4, 1HK5

  • PubMed Abstract: 

    Human serum albumin (HSA) is the major protein component of blood plasma and serves as a transporter for thyroxine and other hydrophobic compounds such as fatty acids and bilirubin. We report here a structural characterization of HSA-thyroxine interactions. Using crystallographic analyses we have identified four binding sites for thyroxine on HSA distributed in subdomains IIA, IIIA, and IIIB. Mutation of residue R218 within subdomain IIA greatly enhances the affinity for thyroxine and causes the elevated serum thyroxine levels associated with familial dysalbuminemic hyperthyroxinemia (FDH). Structural analysis of two FDH mutants of HSA (R218H and R218P) shows that this effect arises because substitution of R218, which contacts the hormone bound in subdomain IIA, produces localized conformational changes to relax steric restrictions on thyroxine binding at this site. We have also found that, although fatty acid binding competes with thyroxine at all four sites, it induces conformational changes that create a fifth hormone-binding site in the cleft between domains I and III, at least 9 A from R218. These structural observations are consistent with binding data showing that HSA retains a high-affinity site for thyroxine in the presence of excess fatty acid that is insensitive to FDH mutations.

  • Organizational Affiliation

    Biophysics Section, Department of Biological Sciences, Imperial College London, South Kensington Campus, United Kingdom.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
SERUM ALBUMIN585Homo sapiensMutation(s): 1 
UniProt & NIH Common Fund Data Resources
Find proteins for P02768 (Homo sapiens)
Explore P02768 
Go to UniProtKB:  P02768
PHAROS:  P02768
GTEx:  ENSG00000163631 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP02768
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.80 Å
  • R-Value Free: 0.245 
  • R-Value Work: 0.203 
  • R-Value Observed: 0.203 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 59.328α = 90
b = 89.284β = 100.8
c = 60.526γ = 90
Software Package:
Software NamePurpose
MOSFLMdata reduction
CCP4data 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: 2003-05-16
    Type: Initial release
  • Version 1.1: 2011-05-08
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2019-07-24
    Changes: Data collection
  • Version 2.0: 2023-11-15
    Changes: Atomic model, Data collection, Database references, Other
  • Version 2.1: 2023-12-13
    Changes: Refinement description