Eat in or take away? How phosphatidylinositol 4-kinases feed the phospholipase C pathway with substrate.
Phosphatidylinositol 4-kinases (PI4Ks) catalyze the first step in the synthesis of phosphoinositide pools hydrolysed by phosphoinositide-dependent phospholipase C (PI-PLC) and thus constitute a potential key regulation point of this pathway. Twelve putative PI4K isoforms, divided as type-II (AtPI4KIIγ1- 8) and type-III PI4Ks (AtPI4KIIIα1- 2 and AtPI4KIIIβ1- 2), have been identified in Arabidopsis genome. By a combination of pharmalogical and genetic approaches we recently evidenced that AtPI4KIIIβ1 and AtPI4KIIIβ2 contribute to supply PI-PLC with substrate and that AtPI4KIIIα1 is probably also involved in this process. Given the current knowledge on PI-PLC and type-III PI4Ks localization in plant cells it raises the question whether type-III PI4Ks produce phosphatidylinositol 4-phosphate at the site of its consumption by the PI-PLC pathway. We therefore discuss the spatial organization of substrate supply to PI-PLC in plant cells with reference to recent data evidenced in mammalian cells.
Université Pierre et Marie Curie (Paris VI), CNRS, EAC7180, UR5 Physiologie Cellulaire et Moléculaire des Plantes, Paris, France.
Elise
E
Delage
Eric
E
Ruelland
Alain
A
Zachowski
Juliette
J
Puyaubert
D019870:1-Phosphatidylinositol 4-Kinase / Q000378:metabolism*; D000818:Animals; D017360:Arabidopsis / Q000201:enzymology / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D008322:Mammals; D010716:Phosphatidylinositols / Q000378:metabolism*; D054801:Phosphoinositide Phospholipase C / Q000378:metabolism*; D020033:Protein Isoforms; D015398:Signal Transduction
D029681:Arabidopsis Proteins; D010716:Phosphatidylinositols; D020033:Protein Isoforms; D019870:1-Phosphatidylinositol 4-Kinase; D054801:Phosphoinositide Phospholipase C