The chaperoning activities of HSP70 and DnaK are regulated by conformational changes associated with interconversion among ATP-bound, ADP-bound, and nucleotide-free states; these are influenced by substrate binding and release, cofactor interactions, and physiologic conditions.
A central goal of molecular biology is to understand the functions of proteins, including their catalytic properties, binding sites, cofactors, interaction partners, and subcellular localization.
Thus, surprisingly, cofactor binding and cofactor-induced conformational changes that promote Ire1 oligomerization can be experimentally uncoupled.
This domain is typically present in Smad transcription factors, where it is found at the C-terminal of the MH1 DNA-binding domain and acts as a protein binding motif that mediates cofactor interactions (Massagué et al. 2005).
Alternatively, this residue might be phosphorylated independent of cofactor binding, with this phosphorylation needed for subsequent phosphorylation induced by cofactor interaction.
All together, we conclude that other factors such as the hormone ligand and the tertiary structure of the NR are crucial players in cofactor binding, and that the contextual interactions are not as important as for other families.
By measuring the Ire1 RNase activity in response to kinase-bound small molecules, we resolved two independent steps in cofactor-Ire1 interactions: cofactor binding and the conformational response to a bound cofactor.
Here, binding of GTP and cofactor magnesium takes place.
AF-1 cofactor recruitment is independent of ligand binding and AF-2 cofactor recruitment is dependent on ligand binding [16].
