Nuclear envelope

• the nuclear envelope enclose DNA
• It contains two concentric membranes (inner & outer membrane) that is penetrated by nuclear pore complexes
• inner membrane contains proteins that act as anchoring sites for chromatin and for the nuclear lamina
• outer membrane is continuous with endoplasmic reticulum and studded with ribsomes
• it contains a perinuclear space
• proteins made here are transported into perinuclear space
• Nuclear envelope during mitosis

  • When nucleus disassembles during mitosis, lamina depolymerises (breaksdown) & nuclear pore complexes disperse in cytosol
  • during this process, some NPC proteins bound to nuclear import receptors - important in reassembly of NPCs at end of mitosis
  • nuclear envelope membrane proteins then disperse throughout ER membrane
  • later in mitosis, nuclear envelope reassembles close to surface of chromosomes