1nqi

X-ray diffraction
2Å resolution

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

Released:

Function and Biology Details

Reactions catalysed:
UDP-alpha-D-galactose + D-glucose = UDP + lactose
UDP-alpha-D-galactose + N-acetyl-beta-D-glucosaminylglycopeptide = UDP + beta-D-galactosyl-(1->4)-N-acetyl-beta-D-glucosaminylglycopeptide
UDP-alpha-D-galactose + N-acetyl-D-glucosamine = UDP + N-acetyllactosamine
Biochemical function:
Cellular component:

Structure analysis Details

Assembly composition:
Non-polymer only dimer (preferred)
Entry contents:
2 distinct polypeptide molecules
Macromolecules (2 distinct):
Alpha-lactalbumin Chains: A, C
Molecule details ›
Chains: A, C
Length: 123 amino acids
Theoretical weight: 14.02 KDa
Source organism: Mus musculus
Expression system: Escherichia coli BL21
UniProt:
  • Canonical: P29752 (Residues: 21-143; Coverage: 100%)
Gene name: Lalba
Sequence domains: C-type lysozyme/alpha-lactalbumin family
Structure domains: Lysozyme
Processed beta-1,4-galactosyltransferase 1 Chains: B, D
Molecule details ›
Chains: B, D
Length: 286 amino acids
Theoretical weight: 32.85 KDa
Source organism: Bos taurus
Expression system: Escherichia coli BL21
UniProt:
  • Canonical: P08037 (Residues: 130-402; Coverage: 68%)
Gene names: B4GALT1, GALT, GGTB2
Sequence domains:
Structure domains: Spore Coat Polysaccharide Biosynthesis Protein SpsA; Chain A

Ligands and Environments

2 bound ligands:

No modified residues

Experiments and Validation Details

Entry percentile scores
X-ray source: NSLS BEAMLINE X9B
Spacegroup: P21
Unit cell:
a: 57.161Å b: 96.379Å c: 99.48Å
α: 90° β: 100.98° γ: 90°
R-values:
R R work R free
0.211 0.21 0.258
Expression system: Escherichia coli BL21