A target of phosphatidylinositol 3,4,5-trisphosphate with a zinc finger motif similar to that of the ADP-ribosylation-factor GTPase-activating protein and two pleckstrin homology domains.
We have purified a protein that binds phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P3] using beads bearing a PtdIns(3,4,5)P3 analogue. This protein, with a molecular mass of 43 kDa, was termed PtdIns(3,4,5)P3-binding protein. The partial amino acid sequences were determined and a full-length cDNA encoding the protein was isolated from bovine brain cDNA library. The clone harbored an open reading frame of 373 amino acids which contained one zinc finger motif similar to that of ADP-ribosylation-factor GTPase-activating protein and two pleckstrin homology domains. The entire sequence was 83% similar to centaurin alpha, another PtdIns(3,4,5)P3-binding protein. The protein bound PtdIns(3,4,5)P3 with a higher affinity than it did inositol 1,3,4,5-tetrakisphosphate, phosphatidylinositol 4,5-bisphosphate, phosphatidylinositol 3,4-bisphosphate, and phosphatidylinositol 3-phosphate suggesting that the binding to PtdIns(3,4,5)P3 was specific. The binding activity was weaker in the mutants with a point mutation in the conserved sequences in each pleckstrin homology domain. Introduction of both mutations abolished the activity. These results suggest that this new binding protein binds PtdIns(3,4,5)P3 through two pleckstrin domains present in the molecule.
Tanaka
K
K
Department of Applied Biological Chemistry, The Graduate School of Agriculture and Life Sciences, University of Tokyo, Bunkyo-ku, Japan.
Imajoh-Ohmi
S
S
Sawada
T
T
Shirai
R
R
Hashimoto
Y
Y
Iwasaki
S
S
Kaibuchi
K
K
Kanaho
Y
Y
Shirai
T
T
Terada
Y
Y
Kimura
K
K
Nagata
S
S
Fukui
Y
Y
D020727:ADP-Ribosylation Factors; D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D001798:Blood Proteins / Q000737:chemistry*; D001923:Brain Chemistry; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000302:isolation & purification; D020558:GTP Phosphohydrolases / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D018129:Phosphatidylinositol Phosphates / Q000737:chemistry / Q000378:metabolism*; D010750:Phosphoproteins; D017386:Sequence Homology, Amino Acid; D016335:Zinc Fingers
D048868:Adaptor Proteins, Signal Transducing; D001798:Blood Proteins; D002352:Carrier Proteins; D018076:DNA, Complementary; D008565:Membrane Proteins; D018129:Phosphatidylinositol Phosphates; D010750:Phosphoproteins; C060974:phosphatidylinositol 3,4,5-triphosphate; C039077:platelet protein P47; C097313:ADP-ribosylation factor related proteins; D020558:GTP Phosphohydrolases; D020727:ADP-Ribosylation Factors