1NQI

crystal structure of lactose synthase, a 1:1 complex between beta1,4-galactosyltransferase and alpha-lactalbumin in the presence of GlcNAc

• PDB DOI: https://doi.org/10.2210/pdb1NQI/pdb
• Entry: 1NQI supersedes: 1J92

• Classification: TRANSFERASE ACTIVATOR/TRANSFERASE
• Organism(s): Mus musculus, Bos taurus
• Expression System: Escherichia coli BL21
• Mutation(s): No 


• Deposited: 2003-01-21 Released: 2003-02-04 
• Deposition Author(s): Ramakrishnan, B., Qasba, P.K.

---

Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.00 Å
• R-Value Free: 0.258 
• R-Value Work: 0.210 
• R-Value Observed: 0.211 

Biological Assembly 1  

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Hetero 2-mer - A1B1 

Biological assembly 1 assigned by authors.

Biological Assembly 2  

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Hetero 2-mer - A1B1 

Biological assembly 2 assigned by authors.

Macromolecule Content

• Total Structure Weight: 94.26 kDa 
• Atom Count: 7,198 
• Modelled Residue Count: 790 
• Deposited Residue Count: 818 
• Unique protein chains: 2

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
ALPHA-LACTALBUMIN	A, C	123	Mus musculus	Mutation(s): 0
UniProt
Find proteins for P29752 (Mus musculus) Explore P29752  Go to UniProtKB:  P29752

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details	Image
BETA-1,4-GALACTOSYLTRANSFERASE	B, D	286	Bos taurus	Mutation(s): 0  EC: 2.4.1.22 (PDB Primary Data), 2.4.1.90 (PDB Primary Data), 2.4.1.38 (PDB Primary Data)
UniProt
Find proteins for P08037 (Bos taurus) Explore P08037  Go to UniProtKB:  P08037

Small Molecules

Ligands 2 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
NAG	F [auth B], H [auth D]	2-acetamido-2-deoxy-beta-D-glucopyranose C8 H15 N O6 OVRNDRQMDRJTHS-FMDGEEDCSA-N
CA	E [auth A], G [auth C]	CALCIUM ION Ca BHPQYMZQTOCNFJ-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.00 Å
• R-Value Free: 0.258 
• R-Value Work: 0.210 
• R-Value Observed: 0.211 
• Space Group: P 1 2₁ 1

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 57.161	α = 90
b = 96.379	β = 100.98
c = 99.48	γ = 90

Software Package:

Software Name	Purpose
DENZO	data reduction
SCALEPACK	data scaling
AMoRE	phasing
CNS	refinement

Structure Validation

Entry History 

Deposition Data

• Released Date: 2003-02-04 
Deposition Author(s): Ramakrishnan, B., Qasba, P.K.
• This entry supersedes: 1J92

Revision History  

• Version 1.0: 2003-02-04
  Type: Initial release
  
• Version 1.1: 2008-04-29
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Non-polymer description, Version format compliance
• Version 1.3: 2020-07-29
  Type: Remediation
  Reason: Carbohydrate remediation
  Changes: Data collection, Derived calculations, Structure summary