Prothymosin alpha is not found in yeast.

According to published accounts, prothymosin alpha exhibits high evolutionary conservation from yeast to man (Makarova, T., Grebenshikov, N., Egorov, C., Vartapetian, A., and Bogdanov, A. FEBS Lett. 257, 247-250, 1989). We report here our failure to find evidence for prothymosin alpha in yeast using three biochemical approaches: hybridization of yeast mRNA and genomic DNA with human prothymosin alpha coding region probes, performance of the polymerase chain reaction with yeast genomic template DNA and three sets of primers recognizing human prothymosin alpha coding region sequences, and isolation of yeast proteins essentially as described in the publication above. A survey of the Saccharomyces cerevisiae complete genome database using the program BLASTp verified our findings: there is no prothymosin alpha-homologue in yeast. Furthermore, DNA representing organisms from bacteria to amphibians also failed to hybridize with the same probes. Therefore, the presence of a prothymosin alpha gene in animals other than mammals is highly unlikely.