Dicty-DymA and Human GBP1 structures
DymA solved by Niemann and colleagues
H-GBP1 solved by Prakash and colleagues
Dicty-DymA is a 96kDa dynamin homologue from Dictyostelium discoideum. It has a similar domain structure to mammalian dynamins but is missing the proline rich domain and the PH domain is replaced by a glutamine and asparagine rich region. A knockout has defects in mitochondrial and endosomal morphology and a defect in cytokinesis. For more information see Niemann et al and references therein.
Human GBP1 is a 67kDa GTP binding protein with antiviral activity. Its expression is induced by interferon-gamma. GBP has an N-terminal GTPase domain, homologous to dynamin but with several inserts in different positions to DymA and other dynamins and the nucleotide is bound in a tilted orientation. The remainder of the protein is purely a-helical and may have a similar structure to dynamin however its sequence similarity is low. For more information see Prakash et al and references therein.
Both these proteins have conserved GTPase domains and show oligomerisation dependent GTPase activity. From the above structures we do not know how these proteins work, but it seems likely that the long helix leaving the GTPase domain could well be a lever arm whose position may change on GTP hydrolysis. (See review for how these proteins fit into the dynamin superfamily.)