Functional expression and characterisation of a new human phosphatidylinositol 4-kinase PI4K230.
By constructing DNA probes we have identified and cloned a human PtdIns 4-kinase, PI4K230, corresponding to a mRNA of 7.0 kb. The cDNA encodes a protein of 2044 amino acids. The C-terminal part of ca. 260 amino acids represents the catalytic domain which is highly conserved in all recently cloned PtdIns 4-kinases. N-terminal motifs indicate multiple heterologous protein interactions. Human PtdIns 4-kinase PI4K230 expressed in vitro exhibits a specific activity of 58 micromol mg-1min-1. The enzyme expressed in Sf9 cells is essentially not inhibited by adenosine, it shows a high Km for ATP of about 300 microM and it is half-maximally inactivated by approximately 200 nM wortmannin. These data classify this enzyme as type 3 PtdIns 4-kinase. Antibodies raised against the N-terminal part moderately activate and those raised against the C-terminal catalytic domain inhibit the enzymatic activity. The coexistence of two different type 3 PtdIns 4-kinases, PI4K92 and PI4K230, in several human tissues, including brain, suggests that these enzymes are involved in distinct basic cellular functions.
Gehrmann
T
T
Ruhr-Universität Bochum, Institut für Physiologische Chemie, Abteilung für Biochemie Supramolekularer Systeme, D-44780, Bochum, Germany.
Gülkan
H
H
Suer
S
S
Herberg
F W
FW
Balla
A
A
Vereb
G
G
Mayr
G W
GW
Heilmeyer
L M
LM
D019870:1-Phosphatidylinositol 4-Kinase / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D002460:Cell Line; D003001:Cloning, Molecular; D006801:Humans; D007527:Isoenzymes / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data
D007527:Isoenzymes; D019870:1-Phosphatidylinositol 4-Kinase