The cytoskeleton is consists of three major type of cytosolic fibers: microtubules, microfilaments (actin filaments), and intermediate filaments, and tubulins comprises the microtubule building block. Tubulin is a globular dimeric protein of alpha/beta chains and it has five distinct forms labeled as -a, -b,-g, -d and -e tubulin. a/b tubulins generates heterodimers which multimerize to form microtubule filaments. Several b tubulin isoforms such as b1, b2, b3, b4, b5, b6, b8 etc have been identified among which b1/b4 are present in cytosol and b2 is present in nuclei/nucleoplasm. d/e tubulins are associated with centrosomes, whereas the g tubulin forms the gammasome, which is required for nucleating microtubule filaments at centrosomes. Several cellular movements are mediated by microtubule action which includes the beating of cilia and flagella, cytoplasmic transport of membrane vesicles, chromosome alignment during meiosis/mitosis, nerve-cell axon migration etc and these movements result from competitive microtubule polymerization/depolymerization or through the actions of microtubule motor proteins.