Electrophoretic analysis of axonally transported proteins in rabbit vagus nerve

Proteins synthesized in the nodose ganglia of rabbits were radiolabeled with 35S-methionine and the proteins present in the vagus nerve, at various times later, were analyzed by SDS (sodium dodecyl sulfate)-polyacrylamide gel electrophoresis. Three major groups of proteins were transported as waves of radioactivity within the nerve at rates of 15-17 mm/h, 12-15 mm/day, and 25-30 mm/day. The front of the fastest wave was composed of two proteins only, of apparent molecular weights 21,000 and 24,000. These were followed after a delay by a number of proteins of higher molecular weight, traveling at the same fast rate. The 25-mm/day wave contained several proteins including a major one of molecular weight 43,000 while the 12-mm/day wave was composed entirely of two proteins of molecular weights 54,000 and 56,000. These groups of slowly transported proteins are therefore similar to those transported much more slowly in other mammalian nerves, with the exception that no proteins with molecular weight similar to the neurofilament proteins could be detected. We have confirmed the dependence of slow transport for both groups of proteins on contact between cell body and axon and suggest that it may be a general phenomenon in all mammalian nerves.