Protein synthesis and transport in the regenerating goldfish visual system

The nature of the proteins synthesized in the goldfish retina and axonally transported to the tectum during optic nerve regeneration has been examined. Electrophoretic analysis of labeled soluble retinal proteins by fluorography verified our previous observation of a greatly enhanced synthesis of the microtubule subunits. In addition, labeling of a tubulin-like protein in the retinal particulate fraction was also increased during regeneration. Like soluble tubulin, the particulate material had an apparent MW of 53-55K and could be tyrosylated in the presence of cycloheximide and [3H]tyrosine. Comparison of post-crush and normal retinal proteins by two-dimensional gel electrophoresis also revealed a marked enhancement in the labeling of two acidic 68-70K proteins. Analysis of proteins slowly transported to the optic tectum revealed changes following nerve crush similar to those observed in the retina, with enhanced labeling of both soluble and particulate tubulin and of 68-70K polypeptides. the most striking change in the profile of rapidly transported protein was the appearance of a labeled 45k protein which was barely detectable in control fish.