Nuclear envelope

The nuclear envelope (synonym = or nuclear membrane) is the double membrane of the nucleus of a eukaryotic cell. The nuclear envelope consists of a double layer of phospholipids and encloses the perinuclear space. The outer membrane is occupied by ribosomes and in some places merges into the endoplasmic reticulum, so that this perinuclear gap connects the nuclear lumen and the endoplasmic reticulum. The nuclear envelope is broken through so-called nuclear pores. A 30-100 nm thick layer of intermediate lamina filaments (nuclear lamina) borders on the inner membrane towards the core interior. The laminin protein family that forms these nuclear lamina is highly conserved during evolution. Lamin filaments stabilize the cell nucleus and serve as fixation for the chromatin filaments. During cell division, the nuclear envelope is dissolved and, after division has occurred, is re-formed around the nuclei of the two daughter cells that have formed. Lamines are involved in the degradation and new formation of the membrane.