In prokaryotes, the incorporation of selenocysteine as the 21st amino acid, encoded by TGA, requires several elements: SelC is the tRNA itself, SelD acts as a donor of reduced selenium, SelA modifies a serine residue on SelC into selenocysteine, and SelB is a selenocysteine-specific translation elongation factor. 3-prime or 5-prime non-coding elements of mRNA have been found as probable structures for directing selenocysteine incorporation. This model describes the elongation factor SelB, a close homolog rf EF-Tu. It may function by replacing EF-Tu. A C-terminal domain not found in EF-Tu is in all SelB sequences in the seed alignment except that from Methanococcus jannaschii. This model does not find an equivalent protein for eukaryotes. [Protein synthesis, Translation factors]
Jiyao W et al.(2023). "The conserved domain database in 2023.",