Effect of triethyllead on post-translational processing of myelin proteins

The effect of triethyllead (PbEt₃) on entry of newly synthesized proteins into myelin was studied in an in vitro system of brain stem slices prepared from actively myelinating young rats. The slices were incubated 30 min with [³H]leucine then the labeling of proteins was halted by a chase with cold amino acid and the slices were incubated an additional 30 min with different concentrations of PbEt₃. Proteins continued to appear in myelin after the chase and this process was inhibited by PbEt₃; however, distinct differences among individual proteins were observed. Inhibition curves for proteolipid, intermediate, and Wolfgram proteins were of a decrementally increasing type and displayed highest inhibition values in the case of proteolipid proteins. On the other hand, deposition of basic proteins was unaffected by the toxin to the concentration of about 5 μm, resulting in a sigmoidal curve of inhibition. The present results indicate specificity of PbEt₃ toward post-translational metabolism of integral myelin proteins.