Molecular determinants of activation and membrane targeting of phosphoinositol 4-kinase IIβ

Gwanghyun Jung, Jing Wang, Pawel Wlodarski, Barbara Barylko, Derk D. Binns, Hongjun Shu, Helen L. Yin, Joseph P. Albanesi

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Mammalian cells contain two isoforms of the type II PI4K (phosphoinositol 4-kinase), PI4KIIα and β. These 55 kDa proteins have highly diverse N-terminal regions (approximately residues 1-90) but conserved catalytic domains (approximately from residue 91 to the C-termini). Nearly the entire pool of PI4KIIα behaves as an integral membrane protein, in spite of a lack of a transmembrane domain. This integral association with membranes is due to palmitoylation of a cysteine-rich motif, CCPCC, located within the catalytic domain. Although the CCPCC motif is conserved in PI4KIIβ, only 50 % of PI4KIIβ is membrane-associated, and approximately half of this pool is only peripherally attached to the membranes. Growth factor stimulation or overexpression of a constitutively active Rac mutant induces the translocation of a portion of cytosolic PI4KIIβ to plasma membrane ruffles and stimulates its activity. Here, we demonstrate that membrane-associated PI4KIIβ undergoes two modifications, palmitoylation and phosphorylation. The cytosolic pool of PI4KIIβ is not palmitoylated and has much lower lipid kinase activity than the membrane-associated kinase. Although only membrane-associated PI4KIIβ is phosphorylated in the unique N-terminal region, this modification apparently does not influence its membrane binding or activity. A series of truncation mutants and α/β chimaeras were generated to identify regions responsible for the isoform-specific behaviour of the kinases. Surprisingly, the C-terminal approx. 160 residues, and not the diverse N-terminal regions, contain the sites that are most important in determining the different solubilities, palmitoylation states and stimulus-dependent redistributions of PI4KIIα and β.

Original languageEnglish (US)
Pages (from-to)501-509
Number of pages9
JournalBiochemical Journal
Volume409
Issue number2
DOIs
StatePublished - Jan 15 2008

Fingerprint

Phosphotransferases
Chemical activation
Membranes
Lipoylation
Catalytic Domain
Protein Isoforms
Phosphorylation
Cell membranes
Solubility
Cysteine
Intercellular Signaling Peptides and Proteins
Membrane Proteins
Cells
Cell Membrane
Association reactions
Lipids
Proteins

Keywords

  • Acyl protein thioesterase 1 (APT1)
  • Catalytic domain
  • Cysteine-rich motif
  • Integral membrane protein
  • Palmitoylation
  • Phosphoinositol 4-kinase (PI4K)

ASJC Scopus subject areas

  • Biochemistry

Cite this

Molecular determinants of activation and membrane targeting of phosphoinositol 4-kinase IIβ. / Jung, Gwanghyun; Wang, Jing; Wlodarski, Pawel; Barylko, Barbara; Binns, Derk D.; Shu, Hongjun; Yin, Helen L.; Albanesi, Joseph P.

In: Biochemical Journal, Vol. 409, No. 2, 15.01.2008, p. 501-509.

Research output: Contribution to journalArticle

Jung, Gwanghyun ; Wang, Jing ; Wlodarski, Pawel ; Barylko, Barbara ; Binns, Derk D. ; Shu, Hongjun ; Yin, Helen L. ; Albanesi, Joseph P. / Molecular determinants of activation and membrane targeting of phosphoinositol 4-kinase IIβ. In: Biochemical Journal. 2008 ; Vol. 409, No. 2. pp. 501-509.
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