The nuclear envelope is a membrane system which surrounds the nucleoplasm of eukaryotic cells. It is composed of the nuclear lamina, nuclear pore complexes and two nuclear membranes. The space between the two membranes is called the nuclear intermembrane space.
The nuclear pore complex (NPC) constitutes the exclusive means of nucleocytoplasmic transport. NPCs allow the passive diffusion of ions and small molecules and the active bidirectional transport of macromolecules such as proteins, RNAs etc across the double-membrane nuclear envelope.The NPC is composed of at least 30 distinct subunits known as Nucleoporins (NUPs).
Required for normal embryogenesis and seed viability. Involved in the first asymmetrical cell division of the zygote. Regulates the number and planes of cell divisions required for generating the normal embryo proper and suspensor, apical-basal axis, cotyledons and meristem. {Experimental EvidencePubMed:15266054, Experimental EvidencePubMed:22898497}.