Selenoproteins are a group of proteins highly conserved through evolution, present in all domains of life. They are characterized for including at least one selenocysteine (Sec, U) amino acid residue in their sequence and most serve oxidoreductase functions. Sec is cotranslationally inserted into nascent polypeptide chains in response to the UGA codon, whose normal function is to terminate translation. To decode UGA as Sec, organisms evolved the Sec insertion machinery that allows incorporation of this amino acid at specific UGA codons in a process requiring a cis-acting Sec insertion sequence (SECIS) elements.

The aim of this project was to identify and characterize Carettochelys insculpta’s selenoproteome by the comparison with Mus Musculus and Anolis carolinensis genomes, in order to shed light on it due to its short knowledge. The data and the results were obtained by using a combination of alignment, sequence extraction tools and computing processing.

A total of 37 proteins were analysed and our findings through the study consist of twelve selenoproteins in Carettochelys insculpta that meet the established criteria: contain a selenocysteine in its sequence and present a SECIS structure at the 3’UTR end. Additionally, six more selenoprotein translation machinery were identified and a Cys-containing homologous protein .

Taken together, this analysis represents a first insight into the selenoproteome of this reptile.