Editing Chaperone (protein) (section)

===Hsp70 and Hsp40===
{{main|Hsp70}}
[[File:Hsp70pocket.png|thumb|hsp70 pocket for substrate binding]]
'''Hsp70''' (DnaK in ''E. coli'') is perhaps the best characterized small (~ 70 kDa) chaperone. The [[Hsp70]] proteins are aided by Hsp40 proteins (DnaJ in ''E. coli''), which increase the ATP consumption rate and activity of the Hsp70s. The two proteins are named "Dna" in bacteria because they were initially identified as being required for ''E. coli'' DNA replication.<ref>{{cite journal |last1=Yochem |first1=J |last2=Uchida |first2=H |last3=Sunshine |first3=M |last4=Saito |first4=H |last5=Georgopoulos |first5=CP |last6=Feiss |first6=M |title=Genetic analysis of two genes, dnaJ and dnaK, necessary for Escherichia coli and bacteriophage lambda DNA replication. |journal=Molecular & General Genetics |date=4 August 1978 |volume=164 |issue=1 |pages=9–14 |doi=10.1007/BF00267593 |pmid=360041|s2cid=28144214 }}</ref>

It has been noted that increased expression of Hsp70 proteins in the cell results in a decreased tendency toward [[apoptosis]]. Although a precise mechanistic understanding has yet to be determined, it is known that Hsp70s have a high-affinity bound state to unfolded proteins when bound to [[Adenosine diphosphate|ADP]], and a low-affinity state when bound to [[Adenosine triphosphate|ATP]].

It is thought that many Hsp70s crowd around an unfolded substrate, stabilizing it and preventing aggregation until the unfolded molecule folds properly, at which time the Hsp70s lose affinity for the molecule and diffuse away.<ref>{{cite journal | vauthors = Mayer MP, Bukau B | title = Hsp70 chaperones: cellular functions and molecular mechanism | journal = Cellular and Molecular Life Sciences | volume = 62 | issue = 6 | pages = 670–84 | date = March 2005 | pmid = 15770419 | pmc = 2773841 | doi = 10.1007/s00018-004-4464-6 }}</ref> Hsp70 also acts as a mitochondrial and chloroplastic molecular chaperone in eukaryotes.