[Karyoskeletal and nuclear envelope proteins in cell cycle progression--known proteins in new functions]

Abstract

The cell nucleus is separated from a cytoplasm by a nuclear envelope (NE) composed of nuclear lamina (NL), outer (ONM) and inner nuclear membrane (INM), connected in the region of nuclear pore complexes (NPC), which are sites for macromolecular transport between the nucleus and the cytoplasm. The nuclear lamina is an essential structure mainly composed of type V intermediate filament proteins, A- and B-type lamins, located between the inner nuclear membrane and the peripheral chromatin. Nuclear envelope, which is composed of integral membrane proteins of the INM (LAP1, LAP2, emerin, MAN1, LBR), has many functions including: connection of nucleoskeleton with cytoskeleton, nuclear lamina meshwork and chromatin. This structure plays a role in maintenance of nuclear shape, spacing of nuclear pore complexes, organization of heterochromatin, DNA replication, and regulation of transcription factors. During cell division NE undergoes depolimerization and reassociation. Latest data suggests, that proteins creating nuclear envelope take part in mitosis.