ABC transporter, vitamin B12 import, permease protein BtuC (IPR023691)

Short name: ABC_transptr_BtuC

Overlapping homologous superfamilies

Family relationships


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.

Most bacterial importers employ a periplasmic substrate-binding protein (PBP) that delivers the ligand to the extracellular gate of the TM domains. These proteins bind their substrates selectively and with high affinity, which is thought to ensure the specificity of the transport reaction. Binding proteins in Gram-negative bacteria are present within the periplasm, whereas those in Gram-positive bacteria are tethered to the cell membrane via the acylation of a cysteine residue that is an integral component of a lipoprotein signal sequence. In planta expression of a high-affinity iron-uptake system involving the siderophore chrysobactin in Erwinia chrysanthemi 3937 contributes greatly to invasive growth of this pathogen on its natural host, African violets [PMID: 8596459]. The cobalamin (vitamin B12) and the iron transport systems share many common attributes and probably evolved from the same origin [PMID: 12475936, PMID: 15475351].

This entry represents bacterial BtuC, which is a component of the vitamin B12 ABC transporter complex [PMID: 3528128]. The BtuC proteins are the membrane-spanning subunits which engage with the ATP binding cassette BtuD. Its crystal structure has been resolved [PMID: 12004122].

GO terms

Biological Process

GO:0015889 cobalamin transport

Molecular Function

No terms assigned in this category.

Cellular Component

GO:0016020 membrane

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.