​Phosphatidylinositol 3-Kinase Class III

Summary

 

Phosphatidylinositol 3-Kinase Class III is a member of the PI3K enzymatic family. All of these proteins act by phosphorylating a hydroxyl group on the third position of phosphatidylinositol, on the inositol ring. PI3KcIII in particular has a role in cell division, membrane traffic and translocation of proteins from the Golgi appartus. Most importantly, this molecule is a vital part of the PI3cIII protein complex, which is necessary for the initiation of autophagy and formation of the autophagosome. This active complex is composed of vps34 (the primary catalytic domain), as well as vps15 (the regulatory domain), Atg6 and Atg14. Upon association of these subunits, the complex is able to phosphorylate PI into PI3P, activating further autophagy cascades.

 

PI3KcIII is highly conserved across variant species, including plants, yeast, drosophila, mice and humans.  The conserved domains found in all species are PI3K C2, the PI3Ka and the PI3/PI4 kinase domains. These are regulatory and representative domains of the PI3K family, and act in combination to produce kinase and transferase action.