SelO and its homologues are widespread among most eukaryotic taxa, and are also common in many major bacterial taxa. SelO is a conserved pseudokinase that transfers AMP from ATP to Ser, Thr, and Tyr residues on protein substrates (AMPylation). It contains a protein kinase fold with ATP flipped in the active site [1]. In eukaryotes, it is a mitochondrial protein that may be involved in redox biology [2].

1: Protein AMPylation by an Evolutionarily Conserved Pseudokinase. Sreelatha A, Yee SS, Lopez VA, Park BC, Kinch LN, Pilch S, Servage KA, Zhang J, Jiou J, Karasiewicz-Urbanska M, Lobocka M, Grishin NV, Orth K, Kucharczyk R, Pawlowski K, Tomchick DR, Tagliabracci VS; Cell. 2018;175:809-821. PMID:30270044

2: Characterization of mammalian selenoprotein o: a redox-active mitochondrial protein. Han SJ, Lee BC, Yim SH, Gladyshev VN, Lee SR; PLoS One. 2014;9:e95518. PMID:24751718