3QKG

Crystal structure of alpha-1-microglobulin at 2.3 A resolution


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.30 Å
  • R-Value Free: 0.260 
  • R-Value Work: 0.213 
  • R-Value Observed: 0.215 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

The crystal structure of human alpha(1)-microglobulin reveals a potential haem-binding site.

Meining, W.Skerra, A.

(2012) Biochem J 445: 175-182

  • DOI: 10.1042/BJ20120448
  • Primary Citation of Related Structures:  
    3QKG

  • PubMed Abstract: 
  • We describe the 2.3 Å (1 Å=0.1 nm) X-ray structure of α1m (α1-microglobulin), an abundant protein in human blood plasma, which reveals the β-barrel fold typical for lipocalins with a deep pocket lined by four loops at its open rim. Loop #1 harbours the residue Cys34 which is responsible for covalent cross-linking with plasma IgA ...

    We describe the 2.3 Å (1 Å=0.1 nm) X-ray structure of α1m (α1-microglobulin), an abundant protein in human blood plasma, which reveals the β-barrel fold typical for lipocalins with a deep pocket lined by four loops at its open rim. Loop #1 harbours the residue Cys34 which is responsible for covalent cross-linking with plasma IgA. A single disulfide bond between Cys72 and Cys169 connects the C-terminal segment to the β-barrel, as in many other lipocalins. The exposed imidazole side chains of His122 and His123 in loop #4 give rise to a double Ni2+-binding site together with a crystallographic neighbour. The closest structural relatives of α1m are the complement protein component C8γ, the L-prostaglandin D synthase and lipocalin 15, three other structurally characterized members of the lipocalin family in humans that have only distant sequence similarity. In contrast with these, α1m is initially expressed as a bifunctional fusion protein with the protease inhibitor bikunin. Neither the electron density nor ESI-MS (electrospray ionization MS) provide evidence for a chromophore bound to the recombinant α1m, also known as 'yellow/brown lipocalin'. However, the three side chains of Lys92, Lys118 and Lys130 that were reported to be involved in covalent chromophore binding appear to be freely accessible to ligands accommodated in the hydrophobic pocket. A structural feature similar to the well-known Cys-Pro haem-binding motif indicates the presence of a haem-binding site within the loop region of α1m, which explains previous biochemical findings and supports a physiological role in haem scavenging, as well as redox-mediated detoxification.


    Organizational Affiliation

    Munich Center for Integrated Protein Science (CIPS-M) and Lehrstuhl für Biologische Chemie, Technische Universität München, Freising-Weihenstephan 85350, Germany.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Protein AMBPA193Homo sapiensMutation(s): 1 
Gene Names: AMBPHCPITIL
UniProt & NIH Common Fund Data Resources
Find proteins for P02760 (Homo sapiens)
Explore P02760 
Go to UniProtKB:  P02760
PHAROS:  P02760
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
GOL
Query on GOL

Download Ideal Coordinates CCD File 
C [auth A]GLYCEROL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
NI
Query on NI

Download Ideal Coordinates CCD File 
B [auth A]NICKEL (II) ION
Ni
VEQPNABPJHWNSG-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.30 Å
  • R-Value Free: 0.260 
  • R-Value Work: 0.213 
  • R-Value Observed: 0.215 
  • Space Group: P 32 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 66.721α = 90
b = 66.721β = 90
c = 80.255γ = 120
Software Package:
Software NamePurpose
MAR345dtbdata collection
MrBUMPphasing
REFMACrefinement
XDSdata reduction
SCALAdata scaling

Structure Validation

View Full Validation Report




Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2012-02-08
    Type: Initial release
  • Version 1.1: 2012-06-20
    Changes: Database references
  • Version 1.2: 2013-06-19
    Changes: Database references
  • Version 1.3: 2017-11-08
    Changes: Refinement description