Ayse Dosemeci

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Calcium/calmodulin-dependent protein kinase II (CaMKII) is a leading candidate for a synaptic memory molecule because it is persistently activated after long-term potentiation (LTP) induction and because mutations that block this persistent activity prevent LTP and learning. Previous work showed that synaptic stimulation causes a rapidly reversible(More)
Postsynaptic densities (PSDs) contain proteins that regulate synaptic transmission. We determined the positions of calcium/calmodulin-dependent protein kinase II (CaMKII) and PSD-95 within the three-dimensional structure of isolated PSDs using immunogold labeling, rotary shadowing, and electron microscopic tomography. The results show that all PSDs contain(More)
Depolarization of rat hippocampal neurons with a high concentration of external potassium induces a thickening of postsynaptic densities (PSDs) within 1.5-3 min. After high-potassium treatment, PSDs thicken 2.1-fold in cultured neurons and 1.4-fold in hippocampal slices compared with their respective controls. Thin-section immunoelectron microscopy of(More)
Postsynaptic density protein 95 (PSD-95), a specialized scaffold protein with multiple protein interaction domains, forms the backbone of an extensive postsynaptic protein complex that organizes receptors and signal transduction molecules at the synaptic contact zone. Large, detergent-insoluble PSD-95-based postsynaptic complexes can be affinity-purified(More)
Cytoskeletal and postsynaptic density (PSD) fractions from forebrain contain discrete spherical structures that are immunopositive for Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). Spherical structures viewed by rotary shadow electron microscopy have an average diameter of approximately 100 nm and, in distinction to postsynaptic densities, do not(More)
A model for the regulation of CaM kinase II is presented based on the following reported properties of the molecule: 1) The holoenzyme is composed of 8-12 subunits, each with the same set of autophosphorylation sites; 2) Autophosphorylation at one group of sites (A sites) requires the presence of Ca2+ and causes a subunit to remain active following the(More)
The major postsynaptic density protein, proposed to be a calcium/calmodulin-dependent protein kinase, becomes phosphorylated when a postsynaptic density preparation from rat cerebral cortex is incubated in medium containing calcium and calmodulin. Upon longer incubation, however, the level of phosphorylation declines, suggesting the presence of a(More)
Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is activated by Ca(2+) entry into neurons. Autophosphorylation of T286 is of special importance because it makes the enzyme active in the absence of Ca(2+), providing a biochemical memory that is critical for plasticity. To understand the factors controlling the duration of this state of CaMKII, we(More)
Phosphorylation of synapsin I by CaMKII has been reported to mobilize synaptic vesicles from the reserve pool. In the present study, the distributions of alpha-CaMKII and of synapsin I were compared in synaptic boutons of unstimulated and stimulated hippocampal neurons in culture by immunogold electron microscopy. CaMKII and synapsin I are located in(More)
We compared the distribution of three scaffolding proteins, all belonging to a family of membrane-associated guanylate kinases, thought to have key roles in the organization of the postsynaptic density (PSD). Isolated PSDs readily adhered to treated glass coverslips where they were labeled with immunogold and rotary shadowed for analysis by EM. The(More)