This entry represents proteins found in the N-terminal region of the essential protein Yae1. Proteins containing this domain include ORAOV1 (Oral cancer-overexpressed protein 1) and YAE1 []. Their function is not clear. In Saccharomyces cerevisiae, Lto1 (ORAOV1 homologue) forms a complex with Rli1 and Yae1, which relieves the toxic effects of reactive oxygen species (ROS) on biogenesis and function of the ribosome [].
Proteins containing this domain (also known as VKOR domain) are from bacteria, plants and archaea. They are homologous to mammalian Vitamin K epoxide reductases (VKORC1). In some plant and bacterial homologues, the VKOR domain is fused with domains of the thioredoxin family of oxidoreductases which may function as redox partners in initiating the reduction cascade []. Proteins containing this domain include Thiol-disulfide oxidoreductase LTO1 (also known as Vitamin K reductase, AtVKOR) from Arabidopsis []and Vitamin K epoxide reductase homologue (VKOR) from Synechococcus sp. [, ]. In general, they disulfide bond-forming enzymes which control disulfide bond formation []. All homologues of VKOR contain an active site CXXC motif, which is switched between reduced and disulfide-bonded states during the reaction cycle [].In Arabidopsis LTO1 catalyses disulfide bond formation of chloroplast proteins and is involved in thylakoid redox regulation and photosynthetic electron transport []. It is required for the assembly of photosystem II (PSII) through the formation of disulfide bond in PSBO, a subunit of the PSII oxygen-evolving complex in the thylakoid lumen []. Bacterial VKOR homologues catalyse disulphide bridge formation in secreted proteins by cooperating with a periplasmic, Trx-like redox partner [, ].
