A palmitoylation code controls PI4KIIIα complex formation and PI(4,5)P2 homeostasis at the plasma membrane

Phosphatidylinositol 4-kinase III alpha (PI4KIII alpha) is the major enzyme responsible for generating phosphatidylinositol (4)-phosphate [PI(4)P] at the plasma membrane. This lipid kinase forms two multicomponent complexes, both including a palmitoylated anchor, EFR3. Whereas both PI4KIII alpha complexes support production of PI(4)P, the distinct functions of each complex and mechanisms underlying the interplay between them remain unknown. Here, we present roles for differential palmitoylation patterns within a tricysteine motif in EFR3B (Cys5, Cys7 and Cys8) in controlling the distribution of PI4KIII alpha between these two complexes at the plasma membrane and corresponding functions in phosphoinositide homeostasis. Spacing of palmitoyl groups within three doubly palmitoylated EFR3B 'lipoforms' affects both interactions between EFR3B and TMEM150A, a transmembrane protein governing formation of a PI4KIII alpha complex functioning in rapid phosphatidylinositol (4,5)-bisphosphate [PI(4,5)P-2] resynthesis following phospholipase C signaling, and EFR3B partitioning within liquid-ordered and -disordered regions of the plasma membrane. This work identifies a palmitoylation code involved in controlling proteinprotein and protein-lipid interactions that affect a plasma membraneresident lipid biosynthetic pathway.

Automated summary

Phosphatidylinositol 4-kinase III alpha (PI4KIII alpha) is responsible for generating phosphatidylinositol (4)-phosphate at the plasma membrane, and the differential palmitoylation patterns of its anchor protein EFR3B control its distribution and phosphoinositide homeostasis.