Dynamin Superfamily members

The dynamin superfamily in humans includes:

Classical dynamins (for example dynamin I),
Dynamin-like proteins (Dlps),
Mx proteins,
OPA1
Mitofusins and
GBP/Atlastin-related proteins.

The minimal domains necessary to belong to the dynamin superfamily are the GTPase, Middle and GED domains. Additional domains are present on most sub-superfamily members to allow specific targeting to sites of action.

Domains are coloured according to the key where those with less sequence homology to dynamin I have a paler colour. A number of superfamily members have transmembrane domains in place of PH-like domains

Dynamin-like proteins (Dlps) are involved in organelle fission and one member is found in each organism from yeast to man. They are found at constricted sites on the outside of the dividing organelle. Mutations in the conserved GTP binding motifs lead to tubulated mitochondria that form elongated networks. For more information see Web pages of Mark McNiven's lab.

OPA1 and Mitofusion are also conserved from yeast to man and involved in mitochonrial fusion. Therefore they act antagonistically to Dlps. OPA1 is found in the mitochondrial inter membrane space wheras Mitofusin is located on the outside of the outer membrane. However, the transmembrane regions of Mitofusion interacts with OPA1. Mutations in OPA1 and mitofusin lead to fragmentation of mitochondria. In case of OPA1 inherited mutations lead to degeneration of optical neurons that result in blindness. (See here for more information on OPA1 mutations)

Mx proteins are only conserved in vertebrates and involved in resistance against viral infections. They are induced by type I interferons and block the replication of a broad spectrum of viruses at various sites in the cell. For more information see Web pages of Otto Haller's lab.

The guanylate-binding proteins are induced by type II interferons and anti-inflammatroy cytokines. An antiviral effect has also been shown but the main function seems to be an anti-proliferatve effect. Many GBPs carry a signal sequence for attachment of a lipid anchor at their C-terminus. Atlastins are neuronal proteins and inherited mutations lead to spastic paraplegia. (see here for more information on Atlastin)

Click here for dynamins in other species:
The first three superfamily members have been shown to oligomerise in vitro in the absence and presence of liposomes (see electron microscopy comparison of dynamin family members) and it is likely that the remaining members do likewise.

*We predict that all superfamily members will show GTPase activation on target-dependent oligomerisation.

*We also propose that all superfamily members will show a lengthwise extension of their oligomers on GTP hydrolysis. This will either lead to scission of the target membrane or a tubulation of the target membrane depending on the rate of hydrolysis.

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