Cell cytoplasm contains protein tubules {microtubule}| to transport molecules.
structure
13 columns of parallel tubulin filaments {protofilament} can combine in linear sequences. Tubulins are globular proteins and are 900-amino-acid biglobular alpha-tubulin and beta-tubulin dimers. Microtubules have 25-nm outside diameter and 14-nm inside diameter. Microtubules contain only water molecules.
forms
Two conformations have different bending around subunit junction: symmetrical form and unstable form. Brain microtubules are stable, but muscle and mitotic microtubules are unstable.
connection
Microtubules connect sideways by proteins {microtubule associated proteins} (MAP).
functions
Vesicles, granules, mitochondria, and chromosomes move along microtubule outsides, using ATPase molecules like kinesins and dyneins. Microtubules are cytoskeleton components, which also have actin and other proteins. Groups of microtubules and other proteins make cilia, flagella, and centrioles. Microtubules make pairs or triples. Cilia have nine triples in circle with middle pair.
anesthetics
Some anesthetics bind to microtubules.
Biological Sciences>Cell>Organelle>Protein
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Date Modified: 2022.0224