Bacteriophage/Gene transfer agent portal protein (IPR006944)

Short name: Phage/GTA_portal

Overlapping homologous superfamilies


Family relationships


This is a family of bacteriophage, prophage and Gene Transfer Agent (GTA) portal proteins. Positioned at one of the twelve icosahedral vertices, of the viral capsid, is a dodecameric complex of the virus encoded portal protein. This dodecameric complex, known as the portal or connector complex, forms the channel through which the viral DNA is packaged into the capsid, and through which it exits during infection. While the portal proteins from different phage show relatively little sequence homology and vary widely in molecular weight, portal complexes display significant morphological similarity as determined by electron microscopy. Morphologically, they present as disk-like structures approximately 150 Angstroms in diameter with radially arranged projections and a 30 Angstroms central channel. The packaging reaction is energy dependent and typically involves several components. ATP hydrolysis provides the driving force, and it is estimated that one ATP molecule is required for every base pair that is packaged. It appears that the portal motor may represent a new and extremely powerful class of motor which couples rotation to DNA translocation [PMID: 11839289].

Contributing signatures

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