Genetic and functional studies of phosphatidyl-inositol 4-kinase type IIIα

Zsofia Szentpetery, G. Szakács, Naveen Bojjireddy, Andrew W. Tai, Tamas Balla

Research output: Contribution to journalArticle

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Abstract

Phosphatidylinositol 4-kinase type IIIa (PI4KIIIα) is one of four mammalian PI 4-kinases that catalyzes the first committed step in polyphosphoinositide synthesis. PI4KIIIα has been linked to regulation of ER exit sites and to the synthesis of plasma membrane phosphoinositides and recent studies have also revealed its importance in replication of the Hepatitis C virus in liver. Two isoforms of the mammalian PI4KIIIα have been described and annotated in GenBank: a larger, ~ 230 kDa (isoform 2) and a shorter splice variant containing only the ~ 97 kDa C-terminus that includes the catalytic domain (isoform 1). However, Northern analysis of human tissues and cancer cells showed only a single transcript of ~ 7.5 kb with the exception of the proerythroleukemia line K562, which contained significantly higher level of the 7.5 kb transcript along with smaller ones of 2.4, 3.5 and 4.2 kb size. Bioinformatic analysis also confirmed the high copy number of PI4KIIIα transcript in K562 cells along with several genes located in the same region in Chr22, including two pseudogenes that cover most exons coding for isoform 1, consistent with chromosome amplification. A panel of polyclonal antibodies raised against peptides within the C-terminal half of PI4KIIIα failed to detect the shorter isoform 1 either in COS-7 cells or K562 cells. Moreover, expression of a cDNA encoding isoform 1 yielded a protein of ∼ 97 kDa that showed no catalytic activity and failed to rescue hepatitis C virus replication. These data draw attention to PI4KIIIα as one of the genes found in Chr22q11, a region affected by chromosomal instability, but do not substantiate the existence of a functionally relevant short form of PI4KIIIα.

Original languageEnglish
Pages (from-to)476-483
Number of pages8
JournalBiochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
Volume1811
Issue number7-8
DOIs
Publication statusPublished - Jul 2011

Fingerprint

1-Phosphatidylinositol 4-Kinase
Phosphatidylinositols
Phosphotransferases
Protein Isoforms
K562 Cells
Hepacivirus
Phosphatidylinositol Phosphates
Chromosomal Instability
Pseudogenes
COS Cells
Nucleic Acid Databases
Virus Replication
Computational Biology
Genes
Exons
Catalytic Domain
Complementary DNA
Chromosomes
Cell Membrane
Antibodies

Keywords

  • Chromosome 22
  • Endoplasmic reticulum
  • Golgi
  • K562 leukemia cells
  • Phosphoinositide
  • PI 4-kinase

ASJC Scopus subject areas

  • Cell Biology
  • Molecular Biology

Cite this

Genetic and functional studies of phosphatidyl-inositol 4-kinase type IIIα. / Szentpetery, Zsofia; Szakács, G.; Bojjireddy, Naveen; Tai, Andrew W.; Balla, Tamas.

In: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids, Vol. 1811, No. 7-8, 07.2011, p. 476-483.

Research output: Contribution to journalArticle

Szentpetery, Zsofia ; Szakács, G. ; Bojjireddy, Naveen ; Tai, Andrew W. ; Balla, Tamas. / Genetic and functional studies of phosphatidyl-inositol 4-kinase type IIIα. In: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids. 2011 ; Vol. 1811, No. 7-8. pp. 476-483.
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