Author/Authors :
Thor Gehrmann، نويسنده , , Hülya Gülkan، نويسنده , , Silke Suer، نويسنده , , Friedrich W. Herberg، نويسنده , , Andras Balla، نويسنده , , Gy?rgy Vereb، نويسنده , , Georg W. Mayr، نويسنده , , Ludwig M. G. HeilmeyerJr، نويسنده ,
Latin Abstract :
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 μmol mg−1 min−1. The enzyme expressed in Sf9 cells is essentially not inhibited by adenosine, it shows a high Km for ATP of about 300 μM 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.
NaturalLanguageKeyword :
activity , expression , sequence , Human phosphatidylinositol 4-kinase
