Multivalent interactions of calcium/calmodulin-dependent protein kinase II with the postsynaptic density proteins NR2B, densin-180, and alpha-actinin-2.
Dendritic calcium/calmodulin-dependent protein kinase II (CaMKII) is dynamically targeted to the synapse. We show that CaMKIIalpha is associated with the CaMKII-binding proteins densin-180, the N-methyl-D-aspartate receptor NR2B subunit, and alpha-actinin in postsynaptic density-enriched rat brain fractions. Residues 819-894 within the C-terminal domain of alpha-actinin-2 constitute the minimal CaMKII-binding domain. Similar ... amounts of Thr286-autophosphorylated CaMKIIalpha holoenzyme [P-T286]CaMKII bind to alpha-actinin-2 as bind to NR2B (residues 1260-1339) or to densin-180 (residues 1247-1495) in glutathione-agarose cosedimentation assays, even though the CaMKII-binding domains share no amino acid sequence similarity. Like NR2B, alpha-actinin-2 binds to representative splice variants of each CaMKII gene (alpha, beta, gamma, and delta), whereas densin-180 binds selectively to CaMKIIalpha. In addition, C-terminal truncated CaMKIIalpha monomers can interact with NR2B and alpha-actinin-2, but not with densin-180. Soluble alpha-actinin-2 does not compete for [P-T286]CaMKII binding to immobilized densin-180 or NR2B. However, soluble densin-180, but not soluble NR2B, increases CaMKII binding to immobilized alpha-actinin-2 by approximately 10-fold in a PDZ domain-dependent manner. A His6-tagged NR2B fragment associates with GST-densin or GST-actinin but only in the presence of [P-T286]CaMKII. Similarly, His6-tagged densin-180 or alpha-actinin fragments associate with GST-NR2B in a [P-T286]CaMKII-dependent manner. In addition, GST-NR2B and His6-tagged alpha-actinin can bind simultaneously to monomeric CaMKII subunits. In combination, these data support a model in which [P-T286]CaMKIIalpha can simultaneously interact with multiple dendritic spine proteins, possibly stabilizing the synaptic localization of CaMKII and/or nucleating a multiprotein synaptic signaling complex.
Mesh Terms:
Actinin, Amino Acid Sequence, Animals, Baculoviridae, Blotting, Western, Calcium-Calmodulin-Dependent Protein Kinase Type 2, Calcium-Calmodulin-Dependent Protein Kinases, Glutathione, Glutathione Transferase, Histidine, Immunoprecipitation, Insecta, Macromolecular Substances, Male, Mice, Molecular Sequence Data, Multiprotein Complexes, Mutation, Neurons, Phosphorylation, Protein Binding, Protein Isoforms, Protein Structure, Tertiary, Rats, Rats, Sprague-Dawley, Receptors, N-Methyl-D-Aspartate, Sepharose, Sialoglycoproteins, Signal Transduction, Swine, Synapses, Threonine, Xenopus
Actinin, Amino Acid Sequence, Animals, Baculoviridae, Blotting, Western, Calcium-Calmodulin-Dependent Protein Kinase Type 2, Calcium-Calmodulin-Dependent Protein Kinases, Glutathione, Glutathione Transferase, Histidine, Immunoprecipitation, Insecta, Macromolecular Substances, Male, Mice, Molecular Sequence Data, Multiprotein Complexes, Mutation, Neurons, Phosphorylation, Protein Binding, Protein Isoforms, Protein Structure, Tertiary, Rats, Rats, Sprague-Dawley, Receptors, N-Methyl-D-Aspartate, Sepharose, Sialoglycoproteins, Signal Transduction, Swine, Synapses, Threonine, Xenopus
J. Biol. Chem.
Date: Oct. 21, 2005
PubMed ID: 16120608
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