Cloning, expression, and localization of 230-kDa phosphatidylinositol 4-kinase.
A phosphatidylinositol (PI) 4-kinase cDNA was cloned from a rat brain cDNA library. This cDNA encoded a protein of 2041 amino acids with a calculated molecular weight of 231,317. The deduced amino acid sequence shared the identity of 52.3 and 34.4% in the presumed catalytic domain with two yeast PI 4-kinases, STT4 and PIK1, respectively, and showed 31.7% identity to p110alpha subunit of rat PI 3-kinase in the same domain. In addition, a 3' half coding region of the present cDNA was 89.6% identical to and its deduced amino acid sequence was 98.2% identical to the sequence for P14Kalpha, a recently reported human PI 4-kinase of type II, suggesting that P14Kalpha is an alternative form of the present PI 4-kinase molecule. The present cDNA contained sequences encoding the ankyrin repeat domain, lipid kinase unique domain, pleckstrin homology domain, presumed lipid kinase/protein kinase homology domain, proline-rich region, and SH3 domain. By examining PI kinase activity in transfected COS-7 cells using the epitope tag immunoprecipitation as well as the conventional way, the product phosphatidylinositol phosphate was identified as phosphatidylinositol 4-phosphate but not phosphatidylinositol 3-phosphate. This PI 4-kinase activity was markedly enhanced in the presence of Triton X-100 but relatively insensitive to inhibition by adenosine. By epitope tag immunohistochemistry, the immunoreactivity for this PI 4-kinase molecule was largely localized in close association with the membranes of the Golgi vesicles and vacuoles. By in situ hybridization analysis, the expression of mRNA for this PI 4-kinase was evident throughout the gray matter of entire brain with higher expression intensity in fetal brain. These data imply that this novel PI 4-kinase is involved in some processes essential to neuronal differentiation and maturation including the synaptogenesis and synaptic plasticity.
Nakagawa
T
T
Department of Anatomy, School of Medicine, Tohoku University, Sendai, Japan.
Goto
K
K
Kondo
H
H
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry; D019204:GTP-Binding Proteins / Q000502:physiology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D051381:Rats
D018076:DNA, Complementary; D017853:Phosphotransferases (Alcohol Group Acceptor); D019204:GTP-Binding Proteins