Alpha-tubulin is not detyrosylated during axonal transport.
We have examined the question of whether alpha-tubulin is detyrosylated during axonal transport in retinal ganglion cell axons and axons of spinal motor neurons. The degree of tyrosylation of alpha-tubulin was estimated from immunocytochemistry and immunoblotting with two anti-alpha-tubulin monoclonals, one of which (YL1/2) recognizes only the tyrosylated form of alpha-tubulin. In the case of retinal ganglion cells, the axons were depleted of tyrosylated alpha-tubulin both in the retina and proximal region of the optic nerve. Distal regions of the axons, in the optic tract, gave a pattern of staining consistent with a reduction in the total level of alpha-tubulin at the expense of detyrosylated alpha-tubulin. Axons within the L5 ventral root, the sciatic nerve and tibial nerve were consistently unstained by YL1/2 indicating that these axons were depleted in tyrosylated alpha-tubulin in all 3 segments. The results indicate that alpha-tubulin destined for axonal microtubules is detyrosylated close to or in cell bodies and not progressively during its transport. Therefore the segregation of detyrosylated alpha-tubulin to axonal microtubules may occur at their site of assembly.
D000818:Animals; D001370:Axonal Transport; D001921:Brain / Q000378:metabolism; D007124:Immunoenzyme Techniques; D007158:Immunologic Techniques; D009046:Motor Neurons / Q000378:metabolism*; D010525:Peripheral Nerves / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012160:Retina / Q000378:metabolism*; D012165:Retinal Ganglion Cells / Q000378:metabolism*; D013116:Spinal Cord / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism*; D014795:Visual Pathways / Q000378:metabolism
D014404:Tubulin; D014443:Tyrosine