Cytoskeletal Signaling: Is Memory Encoded in Microtubule Lattices by CaMKII Phosphorylation?

Memory is attributed to strengthened synaptic connections among particular brain neurons, yet synaptic membrane components are transient, whereas memories can endure. This suggests synaptic information is encoded and ‘hard-wired’ elsewhere, e.g. at molecular levels within the post-synaptic neuron. In long-term potentiation (LTP), a cellular and molecular model for memory, post-synaptic calcium ion (Ca2+) flux activates the hexagonal Ca2+-calmodulin dependent kinase II (CaMKII), a dodacameric holoenzyme containing 2 hexagonal sets of 6 kinase domains. Each kinase domain can either phosphorylate substrate proteins, or not (i.e. encoding one bit). Thus each set of extended CaMKII kinases can potentially encode synaptic Ca2+ information via phosphorylation as ordered arrays of binary ‘bits’. Candidate sites for CaMKII phosphorylation-encoded molecular memory include microtubules (MTs), cylindrical organelles whose surfaces represent a regular lattice with a pattern of hexagonal polymers of the protein tubulin. Using molecular mechanics modeling and electrostatic profiling, we find that spatial dimensions and geometry of the extended CaMKII kinase domains precisely match those of MT hexagonal lattices. This suggests sets of six CaMKII kinase domains phosphorylate hexagonal MT lattice neighborhoods collectively, e.g. conveying synaptic information as ordered arrays of six “bits”, and thus “bytes”, with 64 to 5,281 possible bit states per CaMKII-MT byte. Signaling and encoding in MTs and other cytoskeletal structures offer rapid, robust solid-state information processing which may reflect a general code for MT-based memory and information processing within neurons and other eukaryotic cells

Charon. Les saintes et divines liturgies de nos saints pères Jean Chrysostome, Basile le Grand et Grégoire le Grand, en usage dans Γ Église grecque catholique orientale. Traduction française par le P. Cyrille Charon

Clugnet L. Charon. Les saintes et divines liturgies de nos saints pères Jean Chrysostome, Basile le Grand et Grégoire le Grand, en usage dans Γ Église grecque catholique orientale. Traduction française par le P. Cyrille Charon. In: Revue des Études Grecques, tome 18, fascicule 81,1905. p. 387

Charon. Les saintes et divines liturgies de nos saints pères Jean Chrysostome, Basile le Grand et Grégoire le Grand, en usage dans Γ Église grecque catholique orientale. Traduction française par le P. Cyrille Charon

Clugnet L. Charon. Les saintes et divines liturgies de nos saints pères Jean Chrysostome, Basile le Grand et Grégoire le Grand, en usage dans Γ Église grecque catholique orientale. Traduction française par le P. Cyrille Charon. In: Revue des Études Grecques, tome 18, fascicule 81,1905. p. 387

An exafs and volumetric study of the formation of hydrides on Pd particles encaged in Y-zeolite

EXAFS performed on 10 Å particles of Pd in the network of a Y-zeolite has shown that in vacuum the structure of the metal is similar to that of the bulk.The lattice expansion observed on the EXAFS data when 500 mbar H2 is introduced, is slightly smaller than what is observed on the bulk upon the formation of the β-hydride.It is inferred that on small clusters, where the number of sites is reduced, the stoichiometry of the hydride is reduced to 0.4 H/Pd instead of 0.6

Géographie de la soie,

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