FERROELECTRIC BEHAVIOR IN MICROTUBULE DIPOLE LATTICES - IMPLICATIONS FOR INFORMATION-PROCESSING, SIGNALING AND ASSEMBLY DISASSEMBLY

Cytoskeletal microtubules structurally organize interiors of living eu karyotic cells. As polymers of subunit proteins (''tubulin''), which a re each dipoles, microtubules are thus lattices of oriented dipoles. I n general, three types of arrangements of dipoles in lattices may occu r: (i) random, (ii) ferroelectric (parallel-aligned) and (iii) an inte rmediate weakly ferroelectric phase, which is length-dependent. Becaus e of involvement in dynamical cell activities (movement, growth, mitos is, differentiation, etc.), models of microtubule signaling and inform ation processing have been proposed. In these, tubulin units are assum ed to represent informational ''bit states'' and to be coupled to intr a-tubulin dipoles. In the present paper, we consider microtubules as l attice arrays of coupled local dipole states that interact with their immediate neighbors. Depending on the values of assumed model paramete rs, the system may exhibit ''frustration'': conflict in satisfying all dipole couplings. Such systems have properties suitable for efficient information processing and computation. By slightly altering temperat ure and external field (both within physiological conditions), microtu bule dipole lattices may assume a ferroelectric phase with long-range order and alignment with capabilities to propagate kink-like excitatio ns. The ferroelectric phase appears to be optimal for microtubule sign aling and assembly/disassembly. Microtubules may organize cell activit ies by operating in different modes suitable for information processin g and computation (intermediate phase) or signaling and assembly/disas sembly (ferroelectric phase).