Selenoproteins in the nuclear envelope

Selenium, an essential trace element in mammals, is incorporated as selenocysteine in selenoproteins. Nutritional deficiency decreases the comprehensive biosynthesis of selenoproteins and leads to pathologic conditions. But genetic modifications can also result in the lack of particular selenoproteins. Many of the already characterized selenoproteins act in the regulation of cellular redox processes. But the biological function of some of these proteins, especially with predicted membrane association, remains unknown until now. The nuclear envelope is an important cell compartment in the action of signaling and traffic control between cytoplasm and nuclear interior. It is still unanswered up to now whether selenoproteins play a role in these pathways. In this work we separated nuclear membrane proteins from hepatoma cells by means of an alternative electrophoretic technique for separating membrane proteins namely two dimensional 16-BAC/SDS-PAGE. By metabolic labeling with Se-75 and electrophoresis, the selenoproteome of a nuclear membrane was analysed. In this way three selenoprotein spots could be detected in the nuclear envelopes of JTC-15 cells.