This volume of "Reviews of Physiology" contains three contributions, on Selenium-containing proteins in mammals and other forms of life, on constitutively active and G-protein coupled inward rectifier K+ channels and on Chloroplast quest - a journey from the cytosol into the chloroplast and beyond.

Contributions by: A. Kyriakopoulos, D. Behne, P.R. Stanfield, S. Nakajima, Y. Nakajima, U.C. Vothknecht, J. Soll