Editing Protein complex (section)

==Assembly==

Proper assembly of multiprotein complexes is important, since misassembly can lead to disastrous consequences.<ref>{{cite journal|last1=Dobson|first1=Christopher M|title=Protein folding and misfolding|journal=Nature|date=December 2003|volume=426|issue=6968|pages=884–90|doi=10.1038/nature02261|pmid=14685248|bibcode=2003Natur.426..884D|s2cid=1036192}}</ref> In order to study pathway assembly, researchers look at intermediate steps in the pathway. One such technique that allows one to do that is [[electrospray mass spectrometry]], which can identify different intermediate states simultaneously. This has led to the discovery that most complexes follow an ordered assembly pathway.<ref name = "pmid23582331">{{cite journal |vauthors=Marsh JA, Hernández H, Hall Z, Ahnert SE, Perica T, Robinson CV, Teichmann SA | title = Protein complexes are under evolutionary selection to assemble via ordered pathways | journal = Cell | volume = 153 | issue = 2 | pages = 461–470 | date = Apr 2013 | pmid = 23582331 | doi = 10.1016/j.cell.2013.02.044 | pmc=4009401}}</ref> In the cases where disordered assembly is possible, the change from an ordered to a disordered state leads to a transition from function to dysfunction of the complex, since disordered assembly leads to aggregation.<ref>{{cite journal|last1=Sudha|first1=Govindarajan|last2=Nussinov|first2=Ruth|last3=Srinivasan|first3=Narayanaswamy|title=An overview of recent advances in structural bioinformatics of protein–protein interactions and a guide to their principles|journal=Progress in Biophysics and Molecular Biology|year=2014|volume=116|issue=2–3|pages=141–50|doi=10.1016/j.pbiomolbio.2014.07.004|pmid=25077409}}</ref>

The structure of proteins play a role in how the multiprotein complex assembles. The interfaces between proteins can be used to predict assembly pathways.<ref name = "pmid23582331"/> The intrinsic flexibility of proteins also plays a role: more flexible proteins allow for a greater surface area available for interaction.<ref>{{cite journal|last1=Marsh|first1=Joseph|last2=Teichmann|first2=Sarah A|title=Protein flexibility facilitates quaternary structure assembly and evolution|journal=PLOS Biology|date=May 2014|volume=12|issue=5|doi=10.1371/journal.pbio.1001870|pmid=24866000|pages=e1001870|pmc=4035275 |doi-access=free }}</ref>

While assembly is a different process from disassembly, the two are reversible in both homomeric and heteromeric complexes. Thus, the overall process can be referred to as (dis)assembly.

===Evolutionary significance of multiprotein complex assembly===
In homomultimeric complexes, the [[homomeric]] proteins assemble in a way that mimics evolution. That is, an intermediate in the assembly process is present in the complex's evolutionary history.<ref>{{cite journal|last1=Levy|first1=Emmanuel D|last2=Boeri Erba|first2=Elisabetta|last3=Robinson|first3=Carol V|last4=Teichmann|first4=Sarah A|title=Assembly reflects evolution of protein complexes|journal=Nature|date=July 2008|volume=453|issue=7199|pages=1262–5|doi=10.1038/nature06942|pmid=18563089|pmc=2658002|bibcode=2008Natur.453.1262L}}</ref>
The opposite phenomenon is observed in heteromultimeric complexes, where gene fusion occurs in a manner that preserves the original assembly pathway.<ref name = "pmid23582331"/>