page_title: Septin
section_title: Structure
hierarchical_section_title: Septin / Structure
caption_attribution_description: English: a) schematic of septin molecule with GTP binding domain to one side and the N and C termini of the polypeptide chain to the other b) schematic of septin heterohexameric complex (of human septins), where different septins bind to each other via their GTP binding domains or via the N and C termini. Note the symetry of the complex c) schematic how septin complexes could align to form septin filaments
context_page_description: Septins are a group of GTP-binding proteins expressed in all eukaryotic cells except plants. Different septins form protein complexes with each other. These complexes can further assemble into filaments, rings and gauzes. Assembled as such, septins function in cells by localizing other proteins, either by providing a scaffold to which proteins can attach, or by forming a barrier preventing the diffusion of molecules from one compartment of the cell to another, or in the cell cortex as a barrier to the diffusion of membrane-bound proteins.
  Septins have been implicated in the localization of cellular processes at the site of cell division, and at the cell membrane at sites where specialized structures like cilia or flagella are attached to the cell body. In yeast cells, they compartmentalize parts of the cell and build scaffolding to provide structural support during cell division at the septum, from which they derive their name. Research in human cells suggests that septins build cages around pathogenic bacteria, that immobilize and prevent them from invading other cells.
  As filament forming proteins, septins can be considered part of the cytoskeleton.
context_section_description: Septins are P-Loop-NTPase proteins that range in weight from 30-65 kDa. Septins are highly conserved between different eukaryotic species. They are composed of a variable-length proline rich N-terminus with a basic phosphoinositide binding motif important for membrane association, a GTP-binding domain, a highly conserved Septin Unique Element domain, and a C-terminal extension including a coiled coil domain of varying length.
  Septins interact either via their respective GTP-binding domains, or via both their N- and C-termini. Different organisms express a different number of septins, and from those symmetric oligomeres are formed. For example, in humans Sept7-Sept6-Sept2-Sept2-Sept6-Sept7 form one complex, and in yeast Cdc11-Cdc12-Cdc3-Cdc10-Cdc10-Cdc3-Cdc12-Cdc11 form another one. These complexes then associate to form non-polar filaments, filament bundles, cages or ring structures in cells.
caption: a) schematic of septin molecule with GTP binding domain to one side and the N and C termini of the polypeptide chain to the other
   b) schematic of septin heterohexameric complex (of human septins), where different septins bind to each other via their GTP binding domains or via the N and C termini. Note the symmetry of the complex 
   c) schematic how septin complexes could align to form septin filaments
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