Expression of a Cerebellar Protein (Spot 35 Protein) in Rat Brains

Spot 35 protein is a cerebellar soluble protein with Mr. 27K daltons and pI 5.3, which localizes in Purkinje cells. In order to understand the development of cerebellum at molecular level, it is necessary to reveal the mechanism controlling the biosynthesis of spot 35 protein. Here I examined the developmental and regional changes of mRNA levels for spot 35 protein in rat brain, by using in vitro translation system and dot-blot hybridization with spot 35 protein cDNA as a probe. Dot-blot hybridization analysis revealed that the mRNA in rat cerebellum rapidly increased during postnatal 10-20days and attained a-plateau level after 20days. This result was in agreement with the data of analysis or mRNA level for spot 35 protein by means of in vitro translation system containing rat cerebellar mRNA. The data on spot 35 protein mRNA correlate with the result of immunohistochemical examination using anti-spot 35 protein antiserum. Further, the regions except cerebellum in rat brain contained only negligible Spot 35 protein mRNA. These results suggest a transcriptional control of the concentration of spot 35 protein in developing cerebellum and an intensive expression of its gene in cerebellum