What is Septin? Definition, Types, & Examples

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Septin Definition

Septin is a protein, present in eukaryotes, which bounds to GTP. It takes part in cytokinesis and maintains the structure of cell. While this protein, bounds to the other, it forms a complex such as filament bundles, nonpolar filaments, rings and cages. They maintain the cell structure by forming such complexes.

Within the cell they possess points on which protein can bound themselves. For instance, the main function is providing support when the yeast cells divide, which is done by septum and from this name their name has been derived.

What is Septin?

A septin consist of GTP binding domain, phosphoinositide motif, an N-terminus abundant with proline, a C terminal consisting of coiled domain and a septin unique element domain. They have a weight which ranges from 30-65Kdalton.

In eukaryotes, septin are considered as cytoskeleton, due to the ability of forming filaments. Thus, cytoskeletons are structures which consist of microtubules, microfilaments and intermediate filaments, spectrin and microfilaments. They perform functions such as maintaining the structure of cell, movement of cell and other intracellular functions.

Biological Importance of Septin

Septins form a scaffolding protein complex, after assembling which plays a role in cell division and provides support. Other functions are to separate one compartment from the other, possess points for protein attachment, they restrict movement of molecules within the cell. septins play a role in mitosis and sporulation in yeast cells.

The formation of a ring like structure at septum, during cell division is done by the septins Shs 1, Cdc 3, Cdc 10, Cdc 11 and Cdc 12. Chitin deposition, cytokinesis, mitotic spindle and cell polarity is done by these septins.

The septins engaged in spore formation are the Spr 28 and Spr 3. From recent research done in human cell it is known that as a defense mechanism, septins forms a barrier around the opportunistic microbes so that they don’t tend to damage the other cells.

Other functions of septin are cilium formation, cytokinesis and neurogenesis in humans. To code for septins in humans, 13 genes are required. Septins are further sub-categorized into 4 classes, SEPT 2, which comprises of SEPT 1, 4 and 5. The next class is SEPT 3, which consist of SEPT 9 and SEPT 12.

The next is SEPT 6, which comprises of SEPT 8, 10, 11 and 14. The last one is SEPT 17. However, mutations in such genes may lead to disorders like cancer, Alzheimer’s and others.

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