Schematic representation of the selenocysteine insertion machinery and the selenoprotein detection scheme. (a) A cartoon diagram of selenocysteine incorporation during protein translation inside the cell. The selenocysteine-specific elongation factor (SelB; pink) is shown interacting with the selenocysteine insertion sequence (SECIS) hairpin element in the mRNA and tRNA-sec (SelC). The anticodon of SelC tRNA interacts with and recognizes the 'UGA' codon. The ribosome and other components of the translational machinery are omitted for clarity. (b) Schematic representation of the 'read-through similarity analysis' approach. The top BLAST hit is shown in blue. The window lengths used for the BLAST search and read-through similarity evaluation are marked in the drawing. (c) A flow chart describing how the different components of the predictive scheme are combined for selenoprotein prediction. ORF, open reading frame.