Regulation of type IIalpha phosphatidylinositol phosphate kinase localisation by the protein kinase CK2.
Inositol lipid synthesis is regulated by several distinct families of enzymes [1]. Members of one of these families, the type II phosphatidylinositol phosphate kinases (PIP kinases), are 4-kinases and are thought to catalyse a minor route of synthesis of the multifunctional phosphatidylinositol 4,5-bisphosphate (PI(4,5)P(2)) from the inositide PI(5)P [2]. Here, we demonstrate the partial purification of a protein kinase that phosphorylates the type IIalpha PIP kinase at a single site unique to that isoform - Ser304. This kinase was identified as protein kinase CK2 (formerly casein kinase 2). Mutation of Ser304 to aspartate to mimic its phosphorylation had no effect on PIP kinase activity, but promoted both redistribution of the green fluorescent protein (GFP)-tagged enzyme in HeLa cells from the cytosol to the plasma membrane, and membrane ruffling. This effect was mimicked by mutation of Ser304 to alanine, although not to threonine, suggesting a mechanism involving the unmasking of a latent membrane localisation sequence in response to phosphorylation.
Hinchliffe
K A
KA
Department of Pharmacology Tennis Court Road, Cambridge, CB2 1QJ, UK. kh224@cam.ac.uk
Ciruela
A
A
Letcher
A J
AJ
Divecha
N
N
Irvine
R F
RF
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D047390:Casein Kinase II; D002462:Cell Membrane / Q000201:enzymology / Q000648:ultrastructure; D003600:Cytosol / Q000378:metabolism; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D015778:Minor Histocompatibility Antigens; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000502:physiology; D010766:Phosphorylation; D010768:Phosphoserine / Q000737:chemistry; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D017354:Point Mutation; D020033:Protein Isoforms / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000378:metabolism
D008164:Luminescent Proteins; D008565:Membrane Proteins; D015778:Minor Histocompatibility Antigens; D009363:Neoplasm Proteins; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D010768:Phosphoserine; D017853:Phosphotransferases (Alcohol Group Acceptor); C402182:phosphatidylinositol phosphate 4-kinase; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases