31.5 : Papel das Microtúbulos na Deposição da Parede Celular

Microtubules are small hollow tubes in eukaryotic cells. The cell wall microtubules are polymerized dimers of two globular proteins, α-tubulin and β-tubulin, two globular proteins. With a diameter of about 25 nm, microtubules are the widest components of the cytoskeleton. They help the cell resist compression and provide a track along which vesicles move through the cell or pull replicated chromosomes to opposite ends of a dividing cell. Microtubules go through quick cycles of disassembly and reassembly.

In plant cells, cortical microtubules are known to play a role in depositing cellulose in the cell wall. They influence cellulose deposition by either moving microtubules or directly changing the orientation of newly synthesized cellulose microfibrils. Microfibrils stabilize the boundaries of specialized plasma membrane domains that force nascent cellulose chains into a parallel alignment through glucan chain polymerization and chain crystallization. The glucose monomers form hydrogen bonds, thus holding the cellulose chains firmly together, forming oriented microfibrils. This imparts rigidity in the cell wall during cellulose deposition.

Adapted from section 4.5 cytoskeleton, openstax AP biology, section 6.4 Prokaryotic cell division, Openstax concepts of biology, section 3.2 Carbohydrates, Openstax biology 2 e.