Rapid axoplasmic transport in the olfactory nerve of the pike: II. Analysis of transported proteins by SDS gel electrophoresis

Abstract

Rapidly transported proteins in the olfactory system of the pike Esox lucius were investigated with SDS gel electrophoresis. In order to ascertain the balance of synthesis, transport and turnover, an analysis of different regions of the olfactory system as well as of the peak and plateau regions from the characteristic isotope distribution profile was performed. The following results can be summarized. (1) Due to the morphological uniformity and simplicity of this tissue an unusually simple pattern of labeled, rapidly transported proteins is revealed by electrophoretic separation of nerve and bulb proteins. (2) Three dominant peaks with molecular weights of 118 ± 8, 137 ± 11 and 157 ± 11 kilodaltons contain up to 40% of the total radioactivity while representing only 10% of the total protein. (3) The high radioactivity, fast transport and small protein pool indicate rapid turnover for these proteins. (4) The percentage of the total gel radioactivity in these peaks increases from 18 ± 4% in the proximal nerve segment to 33 ± 4% in the distal segment and 40 ± 5% in the synaptic region. (5) Since the protein content of the high molecular weight peaks remains the same in all nerve regions, the transport system produces a separation of high and low molecular weight proteins during transit from soma to synapse. The high molecular weight proteins are apparently favored to participate in rapid transport.