ABSTRACT
The nuclear envelope (NE) is the hallmark of all eukaryotic cells, separating the nucleoplasm from the cytoplasm during interphase. At the same time, the NE allows for the controlled exchange of macromolecules between the two compartments through nuclear pores and presents a surface for anchoring and organizing cytoskeletal components and chromatin. In order to provide these functions, the NE has evolved into a highly organized system of membranes and proteins. The outer nuclear membrane (ONM) is continuous with the endoplasmic reticulum, while the inner nuclear membrane (INM) contains a number of INM-specific integral and peripheral membrane proteins and is lined by the nuclear lamina in metazoan cells (reviewed by Holaska et al., 2002). While the protein composition of the NE has been studied in detail in animal cells, our knowledge of the components of the plant NE is still at an early stage. To date, only a handful of proteins have been cloned and characterized as components of the plant NE, while a few more have been detected using antibodies against NE components (see Table 1). Initial investigations have revealed similarities as well as striking deviations in the NE biology of the different kingdoms, providing intriguing insights into the evolution of this cell compartment.
