Dynamin [1,2] is a microtubule-associated force-producing protein of 100 Kd which is involved in the production of microtubule bundles and which is able to bind and hydrolyze GTP. Dynamin is structurally related to the following proteins:

• Drosophila shibire protein (gene shi) [3]. Shibire is, very probably, the Drosophila cognate of mammalian dynamin. It seems to provide the motor for vesicular transport during endocytosis.
• Yeast vacuolar sorting protein VPS1 (or SPO15) [4], a protein which could also be involved in microtubule-associated motility.
• Yeast protein MGM1 [5], which is required for mitochondrial genome maintenance.
• Yeast protein DNM1, which is involved in endocytosis.
• Interferon induced Mx proteins [6,7]. Interferon α or β induce the synthesis of a family of closely related proteins. Most of these proteins are known to confer resistance to influenza viruses and/or rhabdoviruses on transfected mammalian cell in culture.

The three motifs found in all GTP-binding proteins are located in the N-terminal part of these proteins. The signature pattern that we developed for these proteins is based on a highly conserved region downstream of the ATP/GTP-binding motif 'A' (P-loop) (see <PDOC00017>).