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RACK1 binds to a signal transfer region of G betagamma and inhibits phospholipase C beta2 activation
Journal article   Open access   Peer reviewed

RACK1 binds to a signal transfer region of G betagamma and inhibits phospholipase C beta2 activation

Songhai Chen, Fang Lin and Heidi E Hamm
The Journal of biological chemistry, Vol.280(39), pp.33445-33452
09/30/2005
DOI: 10.1074/jbc.M505422200
PMID: 16051595
url
https://doi.org/10.1074/jbc.M505422200View
Published (Version of record) Open Access

Abstract

Receptor for Activated C Kinase 1 (RACK1), a novel G betagamma-interacting protein, selectively inhibits the activation of a subclass of G betagamma effectors such as phospholipase C beta2 (PLCbeta2) and adenylyl cyclase II by direct binding to G betagamma (Chen, S., Dell, E. J., Lin, F., Sai, J., and Hamm, H. E. (2004) J. Biol. Chem. 279, 17861-17868). Here we have mapped the RACK1 binding sites on G betagamma. We found that RACK1 interacts with several different G betagamma isoforms, including G beta1gamma1, Gbeta1gamma2, and Gbeta5gamma2, with similar affinities, suggesting that the conserved residues between G beta1 and G beta5 may be involved in their binding to RACK1. We have confirmed this hypothesis and shown that several synthetic peptides corresponding to the conserved residues can inhibit the RACK1/G betagamma interaction as monitored by fluorescence spectroscopy. Interestingly, these peptides are located at one side of G beta1 and have little overlap with the G alpha subunit binding interface. Additional experiments indicate that the G betagamma contact residues for RACK1, in particular the positively charged amino acids within residues 44-54 of G beta1, are also involved in the interaction with PLCbeta2 and play a critical role in G betagamma-mediated PLCbeta2 activation. These data thus demonstrate that RACK1 can regulate the activity of a G betagamma effector by competing for its binding to the signal transfer region of G betagamma.
 Mutation Molecular Sequence Data Recombinant Fusion Proteins - metabolism Type C Phospholipases - antagonists & inhibitors Phospholipase C beta Protein Isoforms - metabolism Receptors for Activated C Kinase Conserved Sequence GTP-Binding Protein beta Subunits - metabolism Binding Sites Maltose-Binding Proteins Binding, Competitive Amino Acid Sequence GTP-Binding Protein gamma Subunits - metabolism Spodoptera - cytology GTP-Binding Protein gamma Subunits - chemistry Mutagenesis, Site-Directed GTP-Binding Protein gamma Subunits - genetics Glutathione Transferase - metabolism Models, Molecular Spectrometry, Fluorescence Neuropeptides - metabolism Sequence Homology, Amino Acid GTP-Binding Protein beta Subunits - chemistry Animals Carrier Proteins - metabolism Escherichia coli - genetics Spodoptera - metabolism Protein Binding Mice Enzyme Activation Isoenzymes - antagonists & inhibitors GTP-Binding Protein beta Subunits - genetics Protein Isoforms - genetics

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