Abstract: Selenium, an essential trace element for human health, plays important roles in maintaining redox balance in vivo. Selenium deficiency is associated with many diseases, such as cancer, neurodegenerative diseases and cardiovascular diseases. The biological function of selenium in vivo is mainly exerted through selenoproteins. Selenoprotein K(SelK) is a newly discovered selenoprotein with unknown biological function and molecular mechanism. In this work, human SelK gene was cloned, site-directedly mutated and inserted into the "bait" plasmid to screen the human liver cDNA library using the yeast two-hybrid system. An interactive protein, homo sapiens cAMP responsive element binding protein 3(CREB3), was screened out and analyzed. SelK' and CREB3 genes were then co-transformed into yeast cells to verify the protein interaction, followed by the co-transfection into HEK293T cells to further verify the interaction via three methods of fluorescence resonance energy transfer technique, including the receptor photobleaching, sensitized emission and fluorescence lifetime. The results show that SelK interacte with CREB3 independent of its selenocysteine residue. By interacting with CREB3, SelK may participate in CREB3-mediated endoplasmic reticulum-asso-ciated degradation and make impact on cancer migration and development.

Key words: Selenoprotein K(SelK), Homo sapiens cAMP responsive element binding protein 3(CREB3), Yeast two hybridization, Fluorescence resonance energy transfer(FRET), Protein-protein interaction