The Selenocysteine-Inserting tRNA Species: Structure and Function

摘要: The occurrence of the amino acid selenocysteine in proteins was first demonstrated for protein A glycine reductase from Clostridium sticklandii 1976, and questions were immediately raised on its mechanism incorporation. At that time, universality 20 proteinogenic acids taken granted, as fact 64 codons "universal" genetic code are assigned either to one these or serve termination signals. Thus, it seemed unlikely would be considered a classical acid. In principle, definition such 21st require (i) incorporation proceeds via cotranslational mechanism, (ii) is directed by specific codon, (iii) tRNA mediates transport ribosome. This chapter illustrates fulfills criteria. It describes unusual structural properties tRNASec, then discusses unique pathway insertion has been worked out Escherichia coli, which finally led proposal model co-translational process at further compares established E. coli with current knowledge mammalian system. Finally, addresses interesting question evolution differs standard many respects.