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Protein Domain : IPR015850

Name	ABC transporter, phosphate import, PstB	Short Name	ABC_transpr_PstB
Type	Domain	Description	ABC transporters belong to the ATP-Binding Cassette (ABC) superfamily, which uses the hydrolysis of ATP to energise diverse biological systems. ABC transporters minimally consist of two conserved regions: a highly conserved ATP binding cassette (ABC) and a less conserved transmembrane domain (TMD). These can be found on the same protein or on two different ones. Most ABC transporters function as a dimer and therefore are constituted of four domains, two ABC modules and two TMDs.ABC transporters are involved in the export or import of a wide variety of substrates ranging from small ions to macromolecules. The major function of ABC import systems is to provide essential nutrients to bacteria. They are found only in prokaryotes and their four constitutive domains are usually encoded by independent polypeptides (two ABC proteins and two TMD proteins). Prokaryotic importers require additional extracytoplasmic binding proteins (one or more per systems) for function. In contrast, export systems are involved in the extrusion of noxious substances, the export of extracellular toxins and the targeting of membrane components. They are found in all living organisms and in general the TMD is fused to the ABC module in a variety of combinations. Some eukaryotic exporters encode the four domains on the same polypeptide chain [].The ABC module (approximately two hundred amino acid residues) is known to bind and hydrolyse ATP, thereby coupling transport to ATP hydrolysis in a large number of biological processes. The cassette is duplicated in several subfamilies. Its primary sequence is highly conserved, displaying a typical phosphate-binding loop: Walker A, and a magnesium binding site: Walker B. Besides these two regions, three other conserved motifs are present in the ABC cassette: the switch region which contains a histidine loop, postulated to polarise the attaching water molecule for hydrolysis, the signature conserved motif (LSGGQ) specific to the ABC transporter, and the Q-motif (between Walker A and the signature), which interacts with the gamma phosphate through a water bond. The Walker A, Walker B, Q-loop and switch region form the nucleotide binding site [, , ].The 3D structure of a monomeric ABC module adopts a stubby L-shape with two distinct arms. ArmI (mainly beta-strand) contains Walker A and Walker B. The important residues for ATP hydrolysis and/or binding are located in the P-loop. The ATP-binding pocket is located at the extremity of armI. The perpendicular armII contains mostly the alpha helical subdomain with the signature motif. It only seems to be required for structural integrity of the ABC module. ArmII is in direct contact with the TMD. The hinge between armI and armII contains both the histidine loop and the Q-loop, making contact with the gamma phosphate of the ATP molecule. ATP hydrolysis leads to a conformational change that could facilitate ADP release. In the dimer the two ABC cassettes contact each other through hydrophobic interactions at the antiparallel beta-sheet of armI by a two-fold axis [, , , , , ].The ATP-Binding Cassette (ABC) superfamily forms one of the largest of all protein families with a diversity of physiological functions []. Several studies have shown that there is a correlation between the functional characterisation and the phylogenetic classification of the ABC cassette [, ]. More than 50 subfamilies have been described based on a phylogenetic and functional classification [, , ]; (for further information see http://www.tcdb.org/tcdb/index.php?tc=3.A.1).This entry represents the C-terminal domain of the ATP-binding subunit of the high-affinity inorganic phosphate transporter Pst. In Escherichia coli, the constitutive transporter for inorganic phosphate, Pit, operates at high phosphate concentrations, while Pit is induced only when extracellular phosphate concentrations are low []. The proteins most similar to the members of this family but not included appear to be amino acid transporters.

Publication Counts Displayer

0 Child Features

0 Contains

1 Cross References

Identifier	Source . Name	Subject . Primary Identifier
PS51238	PROFILE	IPR015850

2 Data Sets

Name	URL
InterPro data set
InterPro GO Annotation data set

3 Found In

DB identifier	Name	Short Name	Type
IPR003593	AAA+ ATPase domain	AAA+_ATPase	Domain
IPR003439	ABC transporter-like	ABC_transporter-like	Domain
IPR005670	Phosphate transport system permease protein 1	Phosp_transpt1	Family

4 GO Annotation

Subject . Secondary Identifier	Subject . Name	Subject . Symbol	Ontology Term . Identifier	Ontology Term . Name
	ABC transporter, phosphate import, PstB		GO:0005524	ATP binding
	ABC transporter, phosphate import, PstB		GO:0015415	phosphate ion transmembrane-transporting ATPase activity
	ABC transporter, phosphate import, PstB		GO:0006817	phosphate ion transport
	ABC transporter, phosphate import, PstB		GO:0016020	membrane

4 Ontology Annotations

Subject . Secondary Identifier	Subject . Name	Subject . Symbol	Ontology Term . Identifier	Ontology Term . Name
	ABC transporter, phosphate import, PstB		GO:0005524	ATP binding
	ABC transporter, phosphate import, PstB		GO:0015415	phosphate ion transmembrane-transporting ATPase activity
	ABC transporter, phosphate import, PstB		GO:0006817	phosphate ion transport
	ABC transporter, phosphate import, PstB		GO:0016020	membrane

0 Parent Features

0 Proteins

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