A UGA stop codon is recoded to accommodate the incorporation of the 21st amino acid selenocysteine (Sec). For a UGA to be recoded a specialized set of cis and trans factors are required and consist of: an mRNA with an in frame UGA codon, a selenocysteine insertion sequence (SECIS) in the 3’ untranslated region (3’ UTR), a SECIS binding protein 2 (SBP2), a specific translation elongation factor (eEFSec), and a selenocysteine tRNA (Sec-tRNA[Ser]Sec). The N-terminus of SBP2 is believed to have no direct role in Sec incorporation because the C terminus of SBP2 is sufficient for the incorporation of Sec into selenoproteins that have one Sec codon. Selenoprotein P (SELENOP) is an essential selenoprotein for male fertility and proper neuron function. SELENOP is also unique in that it contains 10 selenocysteines and is involved in selenium uptake and transport. Interestingly, an in vitro translation system using wheat germ lysate, has no endogenous selenocysteine incorporation factors, cannot synthesize full length SELENOP even when all the known factors are added. The aim of this thesis is to gain insight into the mechanism of processive eukaryotic selenocysteine incorporation by in vitro reconstitution and bioinformatics.