Family With Sequence Similarity 203, Member B (FAM203B)

FAM203B is only found in humans and possibly non-human primates, its paralog, FAM203A, is highly conserved. This protein has no known function yet, although the homolog of FAM203A in Caenorhabditis elegans (Y54H5A.2) is thought to help regulate the actin cytoskeleton. The protein is alanine-, proline-, and leucine-rich, but poor in serine, asparagine, threonine, isoleucine, lysine, and phenylalanine. There are no positive, negative, mixed charge, or hydrophobic clusters; no transmembrane domains; and no clusters of amino acid multiplets. The secondary structure prediction generated by the Phyre 2.0 bioinformatic server shows only α-helices, almost all of which have high confidence values. The phylogenetic tree of FAM203B and its homologs matches with the overall divergence of the respective lineages.