| Annotated protein: | Calcium/calmodulin-dependent protein kinase type II subunit beta (CaM kinase II subunit beta) (CaMK-II subunit beta) (EC 2.7.11.17). Gene symbol: CAMK2B. Taxonomy: Rattus norvegicus (Rat). Uniprot ID: P08413 |
| antibody wiki: | |
| SynGO gene info: | SynGO data @ CAMK2B |
| Ontology domain: | Biological Process |
| SynGO term: | structural constituent of postsynaptic actin cytoskeleton (GO:0098973) |
| Synapse type(s): | hippocampus, glutamatergic |
| Annotated paper: | Okamoto K, et al. "The role of CaMKII as an F-actin-bundling protein crucial for maintenance of dendritic spine structure" Proc Natl Acad Sci U S A. 2007 Apr 10;104(15):6418-23 PMID:17404223 |
| Figure(s): | Figure 1 and 4 |
| Annotation description: | The paper examines the role of CaMKIIb in the bundling of filamentous actin. Figure 1a shows that CaMKIIb can bundle F-actin - F-actin formed in vitro was incubated with purified CaMKIIalpha/beta , alpha , or beta. The reaction product was sedimented, so that the linear, unbundled F-actin stays in supernatant but bundled F-actin sediments. CaMKIIb was pulled-down with the bundled F-actin while the CaMKIIalpha stayed in the supernatant, indicating an interaction between bundled F-actin and CaMKIIb. Figure 1b shows a dose-dependent bundling of F-actin by CaMKIIb. Figure 1c shows negatively stained electron micrographs of F-actin in the presence or absence of purified CaMKIIalpha or CaMKIIb. A clear and strong effect is seen on F-actin bundling when it is incubated with CaMKIIb. Figure 4 shows in-vivo that the interaction between actin and CaMKII slows down the turnover of actin in the dendritic spine. FRAP (fluorescent recovery after photobleaching assay in organotypic hippocampal slices was used to monitor the turnover of actin molecules in dendritic spines. CaMKIIb and GFP-actin were overexpressed. This likely results in CaMKII oligomers that are rich in CaMKIIb. GFP-actin in a single dendritic spine was photobleached and thereafter the recovery of its fluorescence was monitored (Fig. 4a-c). The over expression of CaMKIIb lead to a significantly slower turnover of GFP-actin. CaMKIIalpha, and a deletion mutant of CaMKIIb that does not contain the actin binding site did not have an effect on the recovery time constant (Fig. 4D, E). The conclusion that can be derived here is that CaMKIIb overexpression specifically leads to a slower turnover of actin at dendritic spines. 1/7/2017 Pim - Important is that the bundling activity of CamKIIb does not depend on its kinase activity (Fig.3) - Activation of CamKII is associated with loss of the bundling activity (Fig.5). - "CaMKIIβ but Not -α Is Necessary for Maintaining Synaptic Structure" - Figure 3: The authors show that there are more filopodia and less 'mature dendritic spines' when CaMKII beta is knocked-down. |
| Evidence tracking, Biological System: | Intact tissue Cell-free system |
| Evidence tracking, Protein Targeting: | RNAi / shRNA Over-expression |
| Evidence tracking, Experiment Assay: | Electron Microscopy Two-photon microscopy Fluorescence recovery after photobleaching (FRAP) Western blot |
| Annotator(s): | Noa Lipstein (ORCID:0000-0002-0755-5899) Cordelia Imig (ORCID:0000-0001-7351-8706) Vincent O'connor (ORCID:0000-0003-3185-5709) Nils Brose (ORCID:0000-0003-0938-8534) |
| Lab: | Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany |
| Additional literature: | The paper examines the role of Calcium /Calmodulin kinase II beta (CaMKIIb) in the bundling of filamentous actin (F-actin) and in the regulation of monomeric actin. Figure 1 shows that when recombinant actin is incubated with CaMKIIb or CaMKII(alpha), and the reaction is spun down, the majority of CaMKII(alpha) remains in the supernatant while all the CaMKIIb signal moves to the pellet. This result indicates an association between actin and CaMKIIb, but not CaMKII(alpha). Figure 2 is a structural analysis of the interaction between recombinant CaMKIIb and F-actin. In figure 2A is a CCD image collected on an electron microscope, and in Figure 2b I a slice through a three-dimensional reconstruction obtained using cryoelectron tomography. The images clearly show CaMKIIb associated with the F-actin bundles. Figure 3 shows that CaMKIIb is inhibiting the polymerization of actin monomers into new F-actin filaments. Figure 4 and 5 characterize the binding of CaMKIIb to monomeric actin using fluorescence correlation spectroscopy and fluorescence cross-correlation spectroscopy. Figure 7 shows that when Ca2+/CaM is added, the binding of CaMKIIb to f-Actin is reduced. In summary, the paper shows that CaMKIIb can bind to F-actin, thereby probably stabilizing it, but also to monomeric actin, thereby preventing the generations of new F-actin bundles. @ PMID:19208632 |
| SynGO annotation ID: | 947 |
| Dataset release (version): | 20231201 |
| View annotation as GO-CAM model: |  |