Diacylglycerol kinase delta associates with receptor for activated C kinase 1, RACK1.
The delta-isozyme (type II) of diacylglycerol kinase (DGK) is known to positively regulate growth factor receptor signaling. DGKdelta, which is distributed to clathrin-coated vesicles, interacts with DGKdelta itself, protein kinase C and AP2alpha. To search for additional DGKdelta-interacting proteins, we screened a yeast two-hybrid cDNA library from HepG2 cells using aa 896-1097 of DGKdelta as a bait. We identified aa 184-317 (WD40 repeats 5-7) of receptor for activated C kinase 1 (RACK1), which interacts with various important signaling molecules, as a novel binding partner of DGKdelta. Co-immunoprecipitation analysis, using COS-7 cells co-expressing RACK1 and DGKdelta, revealed that RACK1 selectively interacted with DGKdelta, but not with type I DGKs, in mammalian cells. The interaction was dynamically regulated by phorbol ester. Intriguingly, DGKdelta appeared to recruit RACK1 to clathrin-coated vesicles and co-localized with RACK1. These results suggest that DGKdelta serves as an adaptor protein to regulate the localization of the versatile scaffold protein, RACK1.
Department of Biochemistry, Sapporo Medical University School of Medicine, South-1, West-17, Chuo-ku, Sapporo, 060-8556, Japan.
Shin-Ichi
S
Imai
Satoshi
S
Yasuda
Masahiro
M
Kai
Hideo
H
Kanoh
Fumio
F
Sakane
D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D022163:Clathrin-Coated Vesicles / Q000378:metabolism*; D019852:Diacylglycerol Kinase / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D007668:Kidney / Q000166:cytology / Q000201:enzymology; D008856:Microscopy, Fluorescence; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
D009363:Neoplasm Proteins; C419368:RACK1 protein, human; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface; D019852:Diacylglycerol Kinase; D019204:GTP-Binding Proteins