Dynamin is a GTPase protein responsible for endocytosis in the eukaryotic cell. Dynamin is part of the "dynamin superfamily", which includes classical dynamins, dynamin-like proteins, Mx proteins, OPA1, mitofusins, and GBPs. Members of the dynamin family are principally involved in the scission of newly formed vesicles from the membrane of one cellular compartment and their targeting to, and fusion with, another compartment, both at the cell surface (particularly caveolae internalization) as well as at the Golgi apparatus.[Hinshaw, J. "Research statement, Jenny E. Hinshaw, Ph.D." National Institute of Diabetes & Digestive & Kidney Diseases, Laboratory of Cell Biochemistry and Biology. Accessed 19 March 2013.]
Structure
Dynamin itself is a 96
kilodalton enzyme, and was first isolated when researchers were attempting to isolate new
microtubule-based motors from the bovine brain. Dynamin has been extensively studied in the context of
clathrin-coated vesicle budding from the
cell membrane.
Function
During clathrin-mediated endocytosis, the cell membrane invaginates to form a budding vesicle. Dynamin binds to and assembles around the neck of the endocytic vesicle, forming a helical polymer arranged such that the GTPase domains dimerize in an asymmetric manner across helical rungs.
Types
In mammals, three different dynamin genes have been identified with key sequence differences in their Pleckstrin homology domains leading to differences in the recognition of lipid membranes:
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Dynamin I is expressed in and neuroendocrine cells
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Dynamin II is expressed in most cell types
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Dynamin III is strongly expressed in the testis, but is also present in heart, brain, and lung tissue.
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Pharmacology
Small molecule inhibitors of dynamin activity have been developed, including Dynasore
Disease implications
Mutations in Dynamin II have been found to cause dominant intermediate Charcot-Marie-Tooth disease.
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