Login processing...

Trial ends in Request Full Access Tell Your Colleague About Jove

26.18: Septins

JoVE Core
Cell Biology

A subscription to JoVE is required to view this content. Sign in or start your free trial.


26.18: Septins

Septins are protein filaments forming the cytoskeleton along with the microtubules, microfilaments, intermediate filaments, and other accessory proteins. In 1971 while studying the cell division cycle in mutant Saccharomyces cerevisiae Harwell et al. first identified the septin-related genes playing a crucial role in yeast cytokinesis. Fluorescence microscopy revealed that these proteins localize at the budding neck as rings. These ring-like proteins were then named Septins by John Pringle, and the characterization of these highly conserved cytoskeletal proteins began in the 1980s.

Structure and formation of Septins

Septin monomers can be broadly divided into a variable N-terminal domain, a GTP hydrolyzing domain, and a coiled-coil C-terminal domain. The GTP-binding domain consists of three GTP binding motifs, first G1 or P-loop or Walker A box; second the G3 Switch II and the third G4 for selective binding of GTP. The GTP binding domain ends in a septin unique region (SUR), which comprises 50 amino acid residues and is responsible for helping in septin filament formation.

Classification of Septins

The type and number of septins vary among different organisms. For example, S. cerevisiae has seven, while humans have thirteen. Based on protein sequence similarity, septins are classified into four groups: SEPT2, SEPT3, SEPT6, and SEPT7. In humans, group SEPT2 comprises SEPT1, SEPT2, SEPT4, and SEPT5; group SEPT3 has SEPT3, SEPT9, and SEPT 12; group SEPT6 has SEPT6, SEPT8, SEPT10, and SEPT11; and lastly, group SEPT7 only has SEPT7.

Suggested Reading


Septins Protein Filaments Cytoskeleton Microtubules Microfilaments Intermediate Filaments Accessory Proteins Cell Division Cycle Mutant Saccharomyces Cerevisiae Yeast Cytokinesis Fluorescence Microscopy Budding Neck Rings John Pringle Highly Conserved Cytoskeletal Proteins N-terminal Domain GTP Hydrolyzing Domain Coiled-coil C-terminal Domain GTP Binding Motifs Septin Unique Region (SUR) Septin Filament Formation Classification Of Septins SEPT2 SEPT3 SEPT6 SEPT7

Get cutting-edge science videos from JoVE sent straight to your inbox every month.

Waiting X
Simple Hit Counter