The name is absent

Microtubule lattice structure

Hameroff (1998a, 1998b, 2003a, 2003b) claims in the “Orch OR list of testable
predictions” that the cortical dendrites should contain largely 13A lattice
microtubules compared to 13B lattice microtubules, because 13A lattice
microtubules are preferable for information processing (Tuszynski et al., 1995).

There were experimental data that in vivo assembled microtubules have B lattice
obtained via x-ray scattering by Mandelkow, E. et al. (1977) and electron
microscopy and image reconstruction of microtubules by Mandelkow, E.M., et al.
(1977); Crepeau et al. (1978); McEwen & Edelstein (1980). However with the use
of recombinant motor proteins (kinesin heads) Song & Mandelkow (1993)
decorated microtubules and doublets showing that all brain microtubules have a
B lattice. They questioned the possibility A lattice to exist at all in vivo and
presented data favoring the thesis that all in vivo assembled microtubules have
predominantly B lattice. This meant that microtubules with 13 protofilaments, the
most abundant in vivo, must have a seam where lateral contacts involve
heterologous subunits. Such seam has been directly visualized, both in vivo and
in vitro, using freeze-fracture replicas (Kikkawa et al., 1994). It is strange that
Hameroff (2003b) still insists on 13A lattice importance and defends
experimentally disproved position. Maybe in the near future explanation of what
makes the seam in the 13B microtubules biologically important will be found.

Some of the interesting properties of the 13B lattice is that the transition from
ordered to paraelectric phase happens at higher temperatures than the 13A
lattice because of the existing seam. Another crucial difference is when MAP
attachment to microtubules is considered. MAPs attach themselves to
microtubules in periodic patterns and their function is to stabilize the assembly
properties of the microtubule by preventing the conformational change of the
tubulin dimer to which it is attached. This may be understood by viewing the fixed

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