Eukaryotic porin/Tom40 (IPR027246)

Short name: Porin_Euk/Tom40

Overlapping homologous superfamilies


Family relationships


This entry represents both eukaryotic mitochondrial porins and Tom40 proteins.

Eukaryotic mitochondrial porins are voltage-dependent anion-selective channels (VDAC) that behave as general diffusion pores for small hydrophilic molecules [PMID: 8031826, PMID: 1384178, PMID: 1689252, PMID: 2442148]. The channels adopt an open conformation at low or zero membrane potential and a closed conformation at potentials above 30-40 mV. The eukaryotic mitochondrial porins are beta-barrel proteins, composed of between 12 to 16 beta-strands that span the mitochondrial outer membrane. Yeast contains two members of this family (genes POR1 and POR2); vertebrates have at least three members (genes VDAC1, VDAC2 and VDAC3) [PMID: 8812436]. They are related to the mitochondrial import receptor subunit Tom40 proteins, sharing a common evolutionary origin and structure [PMID: 22178864].

Tom40 is a mitochondrion outer membrane protein and a component of the TOM (translocator of the outer mitochondrial membrane) complex, which is essential for import of protein precursors into mitochondria [PMID: 10427088]. In Saccharomyces cerevisiae, TOM complex is composed of the subunits Tom70, Tom40, Tom22, Tom20, Tom7, Tom6, and Tom5 [PMID: 1327874, PMID: 9774667]. Tom40 is an integral membrane protein and the main structural component of the protein-conducting channel formed by the TOM complex [PMID: 14595396]. It is stabilised by other components, such as Tom5, Tom6, and Tom7 [PMID: 11866524].

GO terms

Biological Process

GO:0055085 transmembrane transport

Molecular Function

No terms assigned in this category.

Cellular Component

GO:0005741 mitochondrial outer membrane

Contributing signatures

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