High levels of prenylated protein methyltransferase are expressed in the developing rat cerebellum and are responsible for methylation of endogenous G-proteins and 50–52 kDa synaptosomal proteins. Enzyme activity in cerebellar synaptosomes of 3 week postnatal rats is 2-fold higher 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' substrates follows the same pattern. The high methyltransferase activity in 3-week-old cerebellum coincides with the period of granule cell migration and synaptogenesis, suggesting a regulatory role for the enzyme and its substrates in cerebellar ontogenesis.
