RACK1, a protein kinase C anchoring protein, coordinates the binding of activated protein kinase C and select pleckstrin homology domains in vitro.
The pleckstrin homology (PH) domain, identified in numerous signaling proteins including the beta-adrenergic receptor kinase (betaARK), was found to bind to various phospholipids as well as the beta subunit of heterotrimeric G proteins (Gbeta) [Touhara, K., et al. (1994) J. Biol. Chem. 269, 10217-10220]. Several PH domain-containing proteins are also substrates of protein kinase C (PKC). Because RACK1, an anchoring protein for activated PKC, is homologous to Gbeta (both contain seven repeats of the WD-40 motif), we determined (i) whether a direct interaction between various PH domains and RACK1 occurs and (ii) the effect of PKC on this interaction. We found that recombinant PH domains of several proteins exhibited differential binding to RACK1. Activated PKC and the PH domain of beta-spectrin or dynamin-1 concomitantly bound to RACK1. Although PH domains bind acidic phospholipids, the interaction between various PH domains and RACK1 was not dependent on the phospholipid activators of PKC, phosphatidylserine and 1, 2-diacylglycerol. Binding of these PH domains to RACK1 was also not affected by either inositol 1,4,5-triphosphate (IP(3)) or phosphatidylinositol 4,5-bisphosphate (PIP(2)). Our in vitro data suggest that RACK1 binds selective PH domains, and that PKC regulates this interaction. We propose that, in vivo, RACK1 may colocalize the kinase with its PH domain-containing substrates.
Rodriguez
M M
MM
Department of Molecular Pharmacology, Stanford University School of Medicine, California 94305-5332, USA.
Ron
D
D
Touhara
K
K
Chen
C H
CH
Mochly-Rosen
D
D
D000818:Animals; D001665:Binding Sites; D001792:Blood Platelets / Q000737:chemistry; D001798:Blood Proteins / Q000737:chemistry / Q000378:metabolism*; D034284:Dynamin I; D034281:Dynamins; D004789:Enzyme Activation; D020558:GTP Phosphohydrolases / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry / Q000378:metabolism; D008956:Models, Chemical; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D010743:Phospholipids / Q000737:chemistry; D010750:Phosphoproteins; D011493:Protein Kinase C / Q000737:chemistry / Q000378:metabolism; D064546:Protein Kinase C beta; D017434:Protein Structure, Tertiary; D051381:Rats; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
D001798:Blood Proteins; D007527:Isoenzymes; D010446:Peptide Fragments; D010455:Peptides; D010743:Phospholipids; D010750:Phosphoproteins; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface; C039077:platelet protein P47; C070301:peptide I; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D034284:Dynamin I; D020558:GTP Phosphohydrolases; D034281:Dynamins