Centrosome A Geometrical Model

The centrosome, the main microtubule organizing center, because of the 9-fold symmetry and the conserved stereotyped geometry of its centrioles, their peculiar (likely unique) orthogonal configuration in S/G2 phase, and their circumferential polarity (the triplets are different and non-equivalent) may play the role of a molecular interface, composed of two orthogonal "9-graduated centrioles/protractors", that recognizes and decodes topogenic targeting sequences and translates them by connecting each one with the corresponding correctly oriented microtubule: targeted molecular complexes (polarity factors, transmembrane receptors, mRNAs) can be delivered into their expected real locations in the cell. The centrosome operates as a spherical reference system organizer, capable of mapping and wiring the cell cortex, polarizing it in detail (fine-tuned polarity) generating a univocal one-to-one correspondence between centrosomal and cortical compartments. One of the two centrioles, named mother, if reversely rotationally polarized, likely constitutes the base for bilateral symmetry.