Editing Protein complex (section)

=== Transient vs permanent/stable protein complex ===
Transient protein complexes form and break down transiently ''in vivo'', whereas permanent complexes have a relatively long half-life. Typically, the obligate interactions (protein–protein interactions in an obligate complex) are permanent, whereas non-obligate interactions have been found to be either permanent or transient.<ref name = "Amoutzias_2010"/> Note that there is no clear distinction between obligate and non-obligate interaction, rather there exist a continuum between them which depends on various conditions e.g. pH, protein concentration etc.<ref name="pmid12853464">{{cite journal |vauthors=Nooren IM, Thornton JM | title = Diversity of protein interactions | journal = EMBO J. | volume = 22 | issue = 14 | pages = 3486–92 |date=July 2003 | pmid = 12853464 | pmc = 165629 | doi = 10.1093/emboj/cdg359 }}</ref> However, there are important distinctions between the properties of transient and permanent/stable interactions: stable interactions are highly conserved but transient interactions are far less conserved, interacting proteins on the two sides of a stable interaction have more tendency of being co-expressed than those of a transient interaction (in fact, co-expression probability between two transiently interacting proteins is not higher than two random proteins), and transient interactions are much less co-localized than stable interactions.<ref name="pmid17535438">{{cite journal |vauthors=Brown KR, Jurisica I | title = Unequal evolutionary conservation of human protein interactions in interologous networks | journal = Genome Biol. | volume = 8 | issue = 5 | pages = R95 | year = 2007 | pmid = 17535438 | pmc = 1929159 | doi = 10.1186/gb-2007-8-5-r95 | doi-access = free }}</ref> Though, transient by nature, transient interactions are very important for cell biology: the human interactome is enriched in such interactions, these interactions are the dominating players of gene regulation and signal transduction, and proteins with ''intrinsically disordered regions'' (IDR: regions in protein that show dynamic inter-converting structures in the native state) are found to be enriched in transient regulatory and signaling interactions.<ref name = "Amoutzias_2010"/>