OmpH Outer membrane protein (OmpH-like)
SMART ACC:	SM000935
Description:	This family includes outer membrane proteins such as OmpH among others. Skp (OmpH) has been characterised as a molecular chaperone that interacts with unfolded proteins as they emerge in the periplasm from the Sec translocation machinery (PUBMED:15304217).
InterPro ACC:	IPR005632
InterPro abstract:	The 17kDa protein Skp (also known as OmpH) of Escherichia coli is a homotrimeric periplasmic chaperone for newly synthesised outer-membrane proteins, the X-ray structure of which has been reported at resolutions of 2.35 A and 2.30 A [ PUBMED:15361861 PUBMED:15304217 … expand The 17kDa protein Skp (also known as OmpH) of Escherichia coli is a homotrimeric periplasmic chaperone for newly synthesised outer-membrane proteins, the X-ray structure of which has been reported at resolutions of 2.35 A and 2.30 A [ PUBMED:15361861 PUBMED:15304217 ]. Three hairpin-shaped α-helical extensions reach out by approximately 60 A from a trimerisation domain, which is composed of three intersubunit β-sheets that wind around a central axis. The α-helical extensions approach each other at their distal turns, resulting in a fold that resembles a 'three-pronged grasping forcep'. The overall shape of Skp is reminiscent of the cytosolic chaperone prefoldin, although it is based on a radically different topology. The peculiar architecture, with apparent plasticity of the prongs and distinct electrostatic and hydrophobic surface properties, supports the recently proposed biochemical mechanism of this chaperone: formation of a Skp(3)-Omp complex protects the outer membrane protein from aggregation during passage through the bacterial periplasm. The ability of Skp to prevent the aggregation of model substrates in vitro is independent of ATP. Skp can interact directly with membrane lipids and lipopolysaccharide. These interactions are needed for efficient Skp-assisted folding of membrane proteins [ PUBMED:15304217 ]. The Haemophilus influenzae member of the family, OMP26, is an outer membrane protein that shows significant potential as a vaccine candidate [ PUBMED:10085039 ]. It is not clear if this protein has undergone adaptive changes in H. influenzae so as to locate to the outer membrane, or if Skp proteins are to some extent peripherally associated with the outer membrane in all species. collapse
GO function:	unfolded protein binding (GO:0051082)
Family alignment:	View the Family alignment or the Alignment consensus sequence
There are 13 114 OmpH domains in 13 106 proteins in SMART's NRDB database.

Taxonomic distribution of proteins containing OmpH domains

The tree below includes only several representative species and genera. The complete taxonomic breakdown of all proteins containing OmpH domains can be accessed here. Click the counts or percentage values to display the corresponding proteins.

Predicted cellular role

Cellular role:	Interaction (with the environment)

Relevant references for this domain

Primary literature for the OmpH domain is listed below. Automatically-derived, secondary literature is also available.

KEGG pathways involving proteins which contain this domain

This information is based on the mapping of SMART genomic protein database to KEGG orthologous groups. Percentages are related to the number of proteins containing a OmpH domain which could be assigned to a KEGG orthologous group, and not all proteins containing OmpH domains. Please note that proteins can be included in multiple pathways, ie. the numbers below will not add to 100%.

KEGG pathways

Some of these pathways are included in the interactive Pathways Explorer overview maps. Select an overview map and click the button below to highlight them in iPath.

KEGG orthologous groups

Some of these KOs are included in the interactive Pathways Explorer overview maps. Select an overview map and click the button below to highlight them in iPath.

3D structures in PDB containing this domain

Links to other resources describing this domain

Pfam	OmpH
InterPro	IPR005632