Non-animal origin of animal thioredoxin reductases: implications for selenocysteine evolution and evolution of protein function through carboxy-terminal extensions.

ABSTRACT: Thioredoxin reductase (TR) and thioredoxin constitute a major cellular redox system present in all organisms. In contrast to a single form of thioredoxin, there are two TR types: One (bacterial type or small TR) is present in bacteria, archaea, plants, and most unicellular eukaryotes, whereas the second (animal or large TR) is only found in animals and typically contains a carboxy-terminal penultimate selenocysteine encoded by TGA. Surprisingly, we detected sequences of large TRs in various unicellular eukaryotes. Moreover, green algae Chlamydomonas reinhardtii had both small and large TRs, with the latter being a selenoprotein, but no examples of horizontal gene transfer from animals to the green algae could be detected. In addition, phylogenetic analyses revealed that large TRs formed a

SUBMITTER: Novoselov SV 

PROVIDER: S-EPMC2312427 | biostudies-literature | 2003 Feb

REPOSITORIES: biostudies-literature