PDBsum entry 1hqp

Signaling protein

PDB id: 1hqp

Contents

Protein chain

149 a.a. *

Ligands

PRZ

* Residue conservation analysis

PDB id:

1hqp

Name:

Signaling protein

Title:

Crystal structure of a truncated form of porcine odorant-binding protein

Structure:

Odorant-binding protein. Chain: a

Source:

Sus scrofa. Pig. Organism_taxid: 9823. Tissue: nasal mucosa

Biol. unit:

Dimer (from PQS)

Resolution:

2.30Å R-factor: 0.204

Authors:

M.Perduca,F.Mancia,R.Del Giorgio,H.L.Monaco

Key ref:

M.Perduca et al. (2001). Crystal structure of a truncated form of porcine odorant-binding protein. Proteins, 42, 201-209. PubMed id: 11119644 DOI: 10.1002/1097-0134(20010201)42:2<201::AID-PROT70>3.3.CO;2-Z

Date:

19-Dec-00 Release date: 17-Jan-01

Protein chain

P81245  (OBP_PIG) -  Odorant-binding protein from Sus scrofa

Seq: 157 a.a.

Struc: 149 a.a.

DOI no: 10.1002/1097-0134(20010201)42:2<201::AID-PROT70>3.3.CO;2-Z

Proteins 42:201-209 (2001)

PubMed id: 11119644

Crystal structure of a truncated form of porcine odorant-binding protein.

M.Perduca, F.Mancia, R.Del Giorgio, H.L.Monaco.

ABSTRACT

The odorant-binding proteins (OBPs) are a family of structurally related molecules that are found in high concentrations in the nasal mucus of vertebrates and bind with moderate affinity a large family of hydrophobic odorants. On the basis of their quaternary structure, the OBPs have been classified as monomers, homodimers, and heterodimers. Porcine OBP was believed for a long time to be a monomer under physiological conditions but there are recent data that support the existence of a monomer-dimer equilibrium. We have determined the crystal structure of a monoclinic form of porcine OBP and found that the truncated molecules, which lack the first 8 amino acids, pack in the cell as dimers that appear to have physiological relevance. The presence in the maps of electron density for an endogenous ligand has also let us identify the side chain of the amino acids that are at the ligand-binding site. In addition, an alternative way of access to the central cavity that binds the ligands is suggested by the particular packing of the molecules in this unit cell. Proteins 2001;42:201-209.

Selected figure(s)

Figure 5.
Figure 5. a: The residual electron density in the cavity of the porcine OBP molecule. Represented is a 2 Fobs-Fc map calculated with phases from the final protein model contoured at a 1 level. Only the 4 amino acids that have density clearly present in this section are represented. b: The position of the endogenous ligand in the internal cavity of the porcine OBP molecule. The ligand is modelled by the canonical odorant 2-isobutyl-3-methoxypyrazine.

Figure 6.
Figure 6. The crystallographic dimer with the bottom monomer replaced by an RBP molecule in approximately the same position and orientation. The retinol ligand is visible with the hydroxyl group on the molecular surface. Notice the position of the loops at the entrance of the central cavity in RBP and the equivalent loops in the porcine OBP molecule.

The above figures are reprinted by permission from John Wiley & Sons, Inc.: Proteins (2001, 42, 201-209) copyright 2001.

Figures were selected by an automated process.