CLONING, CHARACTERIZATION AND EXPRESSION OF THE CDNA-ENCODING A NEURON-SPECIFIC ALPHA-TUBULIN ISOFORM HIGHLY REPRESENTED IN THE ELECTRIC LOBE OF TORPEDO-MARMORATA

A cDNA (alpha T6) encoding an alpha-tubulin from Torpedo marmorata (Tm ) was isolated and sequenced. The deduced 451-amino-acid (aa) sequence codes for an alpha-tubulin of 50161 Da. The aa sequence of alpha T6 o f Tm showed a 70-99.6% identity to the other alpha-tubulins previously described. Moreover, the alpha T6 aa sequence was 95-99.6% identical to neural-specific tubulins of mouse, rat, human and siberian salmon. The corresponding mRNA is highly represented in the giant motoneurons of the electric lobe. All neuronal populations of the Tm brain exhibit variable levels of alpha T6 expression, with the highest levels in th e long-axon-projecting neurons. These results suggest that this alpha- tubulin isoform may play an important role in the maintenance and/or r emodeling of the neuronal cytoskeleton.