Editing Nuclear pore complex (section)

===Theories of assembly===
There are several theories as to how NPCs are assembled. As the immunodepletion of certain protein complexes, such as the Nup 107–160 complex, leads to the formation of poreless nuclei, it seems likely that the Nup complexes are involved in fusing the outer membrane of the nuclear envelope with the inner and not that the fusing of the membrane begins the formation of the pore.{{citation needed|date=May 2024}} There are several ways that this could lead to the formation of the full NPC.
* One possibility is that as a protein complex it binds to the [[chromatin]]. It is then inserted into the double membrane close to the chromatin. This, in turn, leads to the fusing of that membrane. Around this protein complex others eventually bind forming the NPC. This method is possible during every phase of mitosis as the double membrane is present around the chromatin before the membrane fusion proteins complex can insert. Post mitotic cells could form a membrane first with pores being inserted into after formation.{{citation needed|date=May 2024}}
* Another model for the formation of the NPC is the production of a prepore as a start as opposed to a single protein complex. This prepore would form when several Nup complexes come together and bind to the chromatin. This would have the double membrane form around it in during mitotic reassembly. Possible prepore structures have been observed on [[chromatin]] before [[nuclear envelope]] (NE) formation using electron microscopy.<ref>{{cite journal | vauthors = Sheehan MA, Mills AD, Sleeman AM, Laskey RA, Blow JJ | title = Steps in the assembly of replication-competent nuclei in a cell-free system from Xenopus eggs | journal = The Journal of Cell Biology | volume = 106 | issue = 1 | pages = 1–12 | date = January 1988 | pmid = 3339085 | pmc = 2114961 | doi = 10.1083/jcb.106.1.1 }}</ref> During the interphase of the cell cycle the formation of the prepore would happen within the nucleus, each component being transported in through existing NPCs. These Nups would bind to an importin, once formed, preventing the assembly of a prepore in the cytoplasm. Once transported into the nucleus Ran GTP would bind to the importin and cause it to release the cargo. This Nup would be free to form a prepore. The binding of [[importin]]s has at least been shown to bring Nup 107 and the Nup 153 nucleoporins into the nucleus.<ref name="linkinghub.elsevier.com"/> NPC assembly is a very rapid process yet defined intermediate states occur which leads to the idea that this assembly occurs in a stepwise fashion.<ref>{{cite journal |last1=Kiseleva |first1=Elena |last2=Rutherford |first2=Sandra |last3=Cotter |first3=Laura M. |last4=Allen |first4=Terence D. |last5=Goldberg |first5=Martin W. |title=Steps of nuclear pore complex disassembly and reassembly during mitosis in early Drosophila embryos |journal=Journal of Cell Science |date=15 October 2001 |volume=114 |issue=20 |pages=3607–3618 |doi=10.1242/jcs.114.20.3607 |pmid=11707513 }}</ref>