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Catalytic Site Atlas

CSA LITERATURE entry for 1hpm

E.C. nameadenosinetriphosphatase
SpeciesBos taurus (Bovine)
E.C. Number (IntEnz)
CSA Homologues of 1hpmThere are 65 Homologs
CSA Entries With UniProtID
CSA Entries With EC Number
PDBe Entry 1hpm
PDBSum Entry 1hpm
MACiE Entry 1hpm

Literature Report

IntroductionHsc70 is a molecular chaperone of the 70 kilodalton heat shock protein family. It is thought to facilitate protein folding by binding to nascent or misfolding segments of peptide, thus preventing their aggregation. The peptide binding activity is regulated by ATP binding and hydrolysis: with ADP bound Hsc70 binds peptides tightly, but when ATP binds it releases them. The ATPase domain of Hsc70 is located at the N-terminus of the protein and can be isolated as an independent, fully functional entity by proteolysis of the complete protein or as a recombinant expression product.
MechansimHsc70 catalyses ATP hydrolysis by using K+ and Mg2+ to stabilise negative charge in the transition state of phosphoryl transfer. One K+ ion (in site 1, K 490 in structure 1hpm) interacts with the beta phosphate while a second (in site 2, K 491 in structure 1hpm) interacts with the gamma phosphate. Lys 71 is proposed to stabilise a hydroxide ion or water molecule for nucleophilic attack on the gamma phosphate.

Catalytic Sites for 1hpm

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
LysA7171macie:sideChainProposed to stabilise a hydroxide ion or water molecule for nucleophilic attack on the gamma phosphate of ATP.

Literature References

Wilbanks SM
How potassium affects the activity of the molecular chaperone Hsc70. II. Potassium binds specifically in the ATPase active site.
J Biol Chem 1995 270 2251-2257
PubMed: 7836458
Wilbanks SM
Structural replacement of active site monovalent cations by the epsilon-amino group of lysine in the ATPase fragment of bovine Hsc70.
Biochemistry 1998 37 7456-7462
PubMed: 9585559
O'Brien MC
Lysine 71 of the chaperone protein Hsc70 Is essential for ATP hydrolysis.
J Biol Chem 1996 271 15874-15878
PubMed: 8663302