|PROSITE documentation PDOC51719|
The P-loop (see <PDOC00017>) guanosine triphosphatases (GTPases) control a multitude of biological processes, ranging from cell division, cell cycling, and signal transduction, to ribosome assembly and protein synthesis. GTPases exert their control by interchanging between an inactive GDP-bound state and an active GTP-bound state, thereby acting as molecular switches. The common denominator of GTPases is the highly conserved guanine nucleotide-binding (G) domain that is responsible for binding and hydrolysis of guanine nucleotides.
Septins are a family of eukaryotic cytoskeletal proteins conserved from yeasts to humans. The septin family belongs to the guanosine-triphosphate (GTP)ase superclass of P-loop nucleoside triphosphate (NTP)ases. Septins participate in diverse cellular functions including cytokinesis, vesicle trafficking, vesicle fusion, axonal guidance and migration, diffusion barrier, scaffolds, pathogenesis and others. Septin monomers form homo- and hetero-oligomeric complexes that assemble into filaments. Structurally all septins have a GTP-binding domain flanked by N- and C-terminal regions of variable length. The GTP-binding domain is the most highly conserved and is characterized by the presence of three of the five classical GTP-binding motifs. The G1 motif (or Walker A box, GxxxxGKS/T) forms the P-loop, which interacts directly with the nucleotide, whereas the G3 (DxxG) and G4 (xKxD) motifs are respectively essential for Mg(2+) binding and for conferring GTP binding specificity over other nucleotides. The basic structure of the septin-type G domain closely resembles the canonical G domain exemplified by Ras, with six β-strands and five α-helices. A unique feature of the septin-type G domain is the presence of four additional elements compared to Ras (see <PDB:2QA5>). These are the helix α5' between α4 and β6, the two antiparallel strands β7 and β8, and the α6 C-terminal helix that points away from the G domain at a 90° angle relative to the axis of interaction between subunits [1,2,3,4,5].
The profile we developed covers the entire septin-type G domain.Last update:
May 2014 / First entry.
PROSITE method (with tools and information) covered by this documentation:
|1||Authors||Leipe D.D. Wolf Y.I. Koonin E.V. Aravind L.|
|Title||Classification and evolution of P-loop GTPases and related ATPases.|
|Source||J. Mol. Biol. 317:41-72(2002).|
|2||Authors||Versele M. Thorner J.|
|Title||Some assembly required: yeast septins provide the instruction manual.|
|Source||Trends Cell Biol. 15:414-424(2005).|
|3||Authors||Sirajuddin M. Farkasovsky M. Hauer F. Kuehlmann D. Macara I.G. Weyand M. Stark H. Wittinghofer A.|
|Title||Structural insight into filament formation by mammalian septins.|
|4||Authors||Macedo J.N.A: Valadares N.F. Marques I.A. Ferreira F.M. Damalio J.C.P. Pereira H.M. Garratt R.C. Araujo A.P.U.|
|Title||The structure and properties of septin 3: a possible missing link in septin filament formation.|
|Source||Biochem. J. 450:95-105(2013).|
|5||Authors||Zeraik A.E. Rinaldi G. Mann V.H. Popratiloff A. Araujo A.P.U. Demarco R. Brindley P.J.|
|Title||Septins of Platyhelminths: identification, phylogeny, expression and localization among developmental stages of Schistosoma mansoni.|
|Source||PLoS Negl. Trop. Dis. 7:E2602-E2602(2013).|