Comparative Analysis of Rapidly Transported Axonal Proteins in Sensory Neurons of the Frog and Rat

Abstract

35S-labeled proteins carried by fast axonal transport in sciatic sensory axons of bullfrog and rat were separated electrophoretically on discontinuous polyacrylamide gradient slab gels. In contrast to the previously reported similarity in the electrophoretic profiles of rapidly transported proteins from functionally different neurons, we have found that there is very little correspondence in the profiles of these proteins in functionally similar neurons from two widely studied species. We also found very little correspondence between the two species in the profiles of locally synthesized sciatic nerve protein. The results demonstrate the difficulty inherent in comparing the electrophoretic profiles obtained using these two model systems for the study of rapidly transported axonal proteins. In particular, relationships between the major rapidly transported proteins in the two species could not be analyzed with this technique.

Polypeptides in Frog and Rat: Evolutionary Changes in Rapidly Transported and Abundant Nerve Proteins

“…We have compared the most abundant proteins in frog and rat sciatic nerve and a set of less abundant neuronal proteins, namely those that are rapidly transported in frog and rat sciatic nerves. We have adjusted the times allowed for accumulation of rapidly transported proteins at ligatures on frog and rat sciatic nerves to offset the different temperatures of incubation used for the two preparations (Neale et al, 1980). Not every spot on the gels is an independent polypeptide.…”

“…Some studies have suggested that the electrophoretic profiles of rapidly transported proteins in the axons of different species are similar (Theiler et al, 1976;Barker et al, 1977;Bisby, 1977;Skene and Willard, 1981), although differences might have been masked by the lack of resolution and limitation of separation by size alone on the one-dimensional sodium dodecyl sulfate gels used in these studies. Neale et al (1980) reported very little correspondence in the profiles of such proteins from the sensory neurons of frog and rat, but they were unable to distinguish differences arising from alterations in relative abundance and those arising from speciesspecific, transported proteins.…”