PDBsum entry 4zr2

Lipid binding protein

PDB id: 4zr2

Contents

Protein chains

133 a.a.

Ligands

RET

ACT ×5

Waters ×178

PDB id:

4zr2

Name:

Lipid binding protein

Title:

Crystal structure of the domain-swapped dimer k40l:q108k:y60w mutant of human cellular retinol binding protein ii

Structure:

Retinol-binding protein 2. Chain: a, b. Synonym: cellular retinol-binding protein ii,crbp-ii. Engineered: yes. Mutation: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: rbp2, crbp2. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.80Å R-factor: 0.180 R-free: 0.218

Authors:

Z.Assar,Z.Nossoni,J.H.Geiger

Key ref:

Z.Assar et al. (2016). Domain-Swapped Dimers of Intracellular Lipid-Binding Proteins: Evidence for Ordered Folding Intermediates. Structure, 24, 1590-1598. PubMed id: 27524203

Date:

11-May-15 Release date: 08-Jun-16

Protein chains

P50120  (RET2_HUMAN) -  Retinol-binding protein 2 from Homo sapiens

Seq: 134 a.a.

Struc: 133 a.a.*

* PDB and UniProt seqs differ at 3 residue positions (black crosses)

Structure 24:1590-1598 (2016)

PubMed id: 27524203

Domain-Swapped Dimers of Intracellular Lipid-Binding Proteins: Evidence for Ordered Folding Intermediates.

Z.Assar, Z.Nossoni, W.Wang, E.M.Santos, K.Kramer, C.McCornack, C.Vasileiou, B.Borhan, J.H.Geiger.

ABSTRACT

Human Cellular Retinol Binding Protein II (hCRBPII), a member of the intracellular lipid-binding protein family, is a monomeric protein responsible for the intracellular transport of retinol and retinal. Herein we report that hCRBPII forms an extensive domain-swapped dimer during bacterial expression. The domain-swapped region encompasses almost half of the protein. The dimer represents a novel structural architecture with the mouths of the two binding cavities facing each other, producing a new binding cavity that spans the length of the protein complex. Although wild-type hCRBPII forms the dimer, the propensity for dimerization can be substantially increased via mutation at Tyr60. The monomeric form of the wild-type protein represents the thermodynamically more stable species, making the domain-swapped dimer a kinetically trapped entity. Hypothetically, the wild-type protein has evolved to minimize dimerization of the folding intermediate through a critical hydrogen bond (Tyr60-Glu72) that disfavors the dimeric form.