A 20-residue peptide corresponding to the C-terminal amino acid sequence of rat nestin was synthesized by the solid phase method. The anti-peptide antibody (designated Anti-Nes-2) against nestin was prepared. Western blots showed that Anti-Nes-2 recognized not only mouse nestin with a MW of 240 kD but also a band with a MW of 50 kD. N-terminal amino acid sequence showed that this 50 kD protein is alpha-tubulin. Western blots with Anti-Nes-2 and with monoclonal antibodies against alpha- and beta-tubulin revealed that this 50 kD band could only be detected in different stages of mouse brain and in the primary culture of neural precursor cells (NPCs), with higher expression during the development of mouse brain and the maturation of NPCs; whereas alpha- and beta-tubulin were expressed in different cell lines and tissues of adult mouse. Taken together, these results indicate that 50 kD protein recognized by Anti-Nes-2 is a neuron-specific alpha-tubulin and could be a neuron-specific posttranslational modification isotype of alpha-tubulin.