Palindromic assembly of the giant muscle protein titin in the sarcomeric Z-disk

The Z-disk of striated and cardiac muscle sarcomeres is one of the most densely packed cellular structures in eukaryotic cells. It provides the architectural framework for assembling and anchoring the largest known muscle filament systems by an extensive network of protein-protein interactions, requiring an extraordinary level of mechanical stability. Here we show, using X-ray crystallography, how the amino terminus of the longest filament component, the giant muscle protein titin, is assembled into an antiparallel (2:1) sandwich complex by the Z-disk ligand telethonin. The pseudosymmetric structure of telethonin mediates a unique palindromic arrangement of two titin filaments, a type of molecular assembly previously found only in protein-DNA complexes. We have confirmed its unique architecture in vivo by protein complementation assays, and in vitro by experiments using fluorescence resonance energy transfer. The model proposed may provide a molecular paradigm of how major sarcomeric filaments are crosslinked, anchored and aligned within complex cytoskeletal networks

Language processing with dynamic fields

We construct a mapping from complex recursive linguistic data structures to spherical wave functions using Smolensky's filler/role bindings and tensor product representations. Syntactic language processing is then described by the transient evolution of these spherical patterns whose amplitudes are governed by nonlinear order parameter equations. Implications of the model in terms of brain wave dynamics are indicated