Molecular biology of tubulin: Its interaction with drugs and genomic organization.
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Date
1984-10
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Abstract
Microtubules are ubiquitous cellular structures found in eukaryotic organisms and
responsible for a variety of functions. These functions include mitosis, motility, cytoskeletal
architecture, intracellular transport and secretion. The major structural component of
microtubules is tubulin, a dimeric protein molecule consisting of two similar but nonidentical
subunits (α and β) each of about molecular weight 55,000. With the introduction of radioactive
colchicine for the first time it has been reported that colchicine binds specifically to tubulin. At
this point microtubule research stepped up to a new era linking microtubules with other
spindle poisons which are structurally diverse as well as binding at different sites on to the
tubulin heterodimer. These antimicrotubular agents have already provided valuable information
regarding microtubule-mediated cellular functions and its association and dissociation
phenomena. Tubulins appear to be conserved proteins based on in vitro copolymerization and
comigration on polyacrylamide gel electrophoretic properties. Further, amino acid sequences
of both α and β subunits from a variety of sources also appear to be mostly conserved. The
evolutionary conservation of tubulin genes is highly reflected at the nucleic acid level as well.
The estimation of the number of genes for tubulin and their organization in a variety of organisms
have opened up a new dimension to microtubule and tubulin research. The multigene family
for tubulins comprising also pseudogenes is suggestive that more than one gene for each α and
β tubulin is functional in the cell. Therefore, it has been speculated that different tubulin gene
products contribute to functionally different microtubules at specific stages in cell cycle and cell
growth. Heterogeneity in both α and β tubulins has already been established during different
stages of development of the cell. Obviously, it reflects that tubulin genes are highly regulated
and this regulation might be at the transcriptional and/or translational level. Whatever is the
actual control mechanism it appears that cells can detect an enhanced pool of depolymerized
subunits and a rapid and specific control in tubulin gene expression at the transcriptional
and/or post transcriptional level does occur.
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Keywords
Tubulin, microtubule, drugs, tubulin mRNA, cDNA, pseudogene, evolution
Citation
Biswas B B, Sen K, Choudhury G Ghosh, Bhattacharyya B. Molecular biology of tubulin: Its interaction with drugs and genomic organization. Journal of Biosciences. 1984 Oct; 6(4): 431-457.