CHARACTERIZATION OF A TRYPANOSOMA-CRUZI POLY(A)-BINDING PROTEIN AND ITS GENES

We have characterized the biochemical properties of a 66-kDa poly(A)-b inding protein (PABP1) in the protozoan Trypanosoma cruzi and isolated two classes of cDNAs encoding the protein. In concordance, Southern b lots showed the presence of 2 gene copies. The two cDNA classes differ in the length of adenosine-rich segments in the 5' untranslated regio n and in point changes scattered throughout the sequence, but their 16 50-bp open reading frames encode identical proteins. A single mRNA of 5.5 kb was detected, indicating that the noncoding regions are unusual ly long. Both the mRNA and the protein are constitutively expressed in all stages of T. cruzi life cycle. The biochemical properties and seq uence comparisons show that the T. cruzi PABP1 is similar to the PABP1 of other eukaryotic organisms. These results indicate that PABP1 has been conserved throughout eukaryotic evolution.