ULTIMATE COMPUTING - Quantum Consciousness Studies

Cytoskeleton/Cytocomputer 85
within large animals. The protein subunits assemble in longitudinal strings called
protofilaments; thirteen parallel protofilaments laterally align to form the hollow
“tubules.” The subunits are “barbell shaped” proteins (“dimers”) which in turn
consist of two globular proteins (“monomers”) known as alpha and beta tubulin
(Figure 5.4). Alpha and beta tubulin monomers are similar molecules with
identical orientation within protofilaments and tubule walls. Each monomer
consists of about 500 amino acids, weighs about 55 kilodaltons (Chapter 6), and
has a local polarity or charge orientation. MT which grow from cell centers have a
plus end (beta tubulin) which extends outward from the cell center
(“centrosome”) into the cell periphery. The minus end (alpha tubulin) remains
anchored to a microtubule organizing center (MTOC) within the centrosome.
Each dimer, as well as each MT, appears to have an electrical polarity or dipole,
with the negative end oriented towards the alpha monomer and cell center, and
the positive end towards the beta monomer and cell periphery.
Figure 5.4: Microtubules are cylinders whose walls are 13 protofilaments, each a
string of 8 nm tubulin dimers. Alpha and beta tubulin monomers form the dimers.
Each dimer has 6 neighbors. By Fred Anderson.
The dimers are held together by relatively weak Van der Waals hydrophobic
forces such as dipole coupling (Chapter 6). Dimer neighbors form hexagonal