PRENYLATED PROTEIN METHYLTRANSFERASE OF RAT CEREBELLUM IS DEVELOPMENTALLY COEXPRESSED WITH ITS SUBSTRATES

High levels of prenylated protein methyltransferase are expressed in t he developing rat cerebellum and are responsible for methylation of en dogenous G-proteins and 50-52 kDa synaptosomal proteins. Enzyme activi ty in cerebellar synaptosomes of 3 week postnatal rats is 2-fold highe r than that found in adult rat cerebellum. A 10-fold rise in activity occurs at the end of the second and during the third postnatal weeks, followed by a subsequent decline. Expression of the enzymes' substrate s follows the same pattern. The high methyltransferase activity in 3-w eek-old cerebellum coincides with the period of granule cell migration and synaptogenesis, suggesting a regulatory role for the enzyme and i ts substrates in cerebellar ontogenesis.