Evidence for unusually short tubulin mRNA leaders and characterization of tubulin genes in Giardia lamblia.

We have cloned alpha- and beta-tubulin cDNAs from Giardia lamblia and have used these to determine the gene copy number in the organism and to isolate alpha- and beta-tubulin genomic clones. Studies of the gene organization demonstrate that two copies of beta-tubulin are linked in a head-to-head configuration. The DNA from these two copies and that from one alpha-tubulin copy has been sequenced upstream of the translation initiation codon, and analyzed for consensus to typical eukaryotic promoter sequences. Characterization of the alpha- and beta-tubulin mRNAs in this parasite by primer extension and S1 nuclease mapping has revealed an unusually short (6 nucleotides) 5' untranslated region.