Cloning and sequencing of the rat cDNAs encoding class I beta-tubulin

Two kinds of rat cDNA clones encoding class I beta-tubulin were isolated from the neonatal rat brain, and sequenced. They corresponded to mRNA species formed by the alternative usage of polyadenylation signals. The determined nucleotide sequence showed high (84.6%) identity to rat class II beta-tubulin, the only rat beta-tubulin sequence reported in the nucleotide database, in the coding region, but relatively low (47.3-50.7%) in the noncoding region. The Northern blot analysis using the 3'-noncoding fragment as a probe showed that both mRNA species of the class I beta-tubulin were down-regulated during brain development.