Many reagents have bell-shaped curves through action on multiple, counter-balanced targets or even binding at multiple-sites on a single target; this may explain the bell-shaped curves of the seven compounds tested here that were not observed to aggregate (Supplementary Table S3).
However, as previously suggest, replacement of iron by copper, and binding of copper at multiple sites on the protein might lead to aggregation of the protein.
AMPK is activated by phosphorylation of Thr172 within the kinase domain by upstream kinases, with the principal upstream kinase being the tumor suppressor LKB1 [4 6], and/or by binding of allosteric activators at multiple sites [7].
The formation of a number of complexes of different molecular weights as JAZ protein is added to the RNA is most likely because of the binding of the protein at multiple sites on the RNA, with each of these sites having comparable but slightly different affinity.
Each of these proteins had large binding regions which offered ample room for the ligand to bind in multiple conformations and at multiple sites within the binding region of the protein.
Upon ligand-binding, PR is globally phosphorylated at multiple sites, as indicated by a slight gel upshift [ 42].
Thus, efficient Slimb binding and Ci processing require phosphorylation at multiple sites by three kinases, rendering Ci proteolysis very sensitive to Hh regulation.
NF κB mediates cell-cycle progression through direct binding of the cyclin D1 promoter at multiple sites and regulates progression through G1-S cell-cycle check point (Guttridge et al, 1999).
Akt kinases phosphorylate FOXO at multiple sites and create binding sites for 14-3-3 14-3-3 14-3-3sing sequestration of FOXO factors in the cytosol [ 26].
The continued development of biophysical technologies, such as SPR, that can support measurement of low-affinity ligands, perhaps at multiple sites on a binding partner without total dependence on X-ray crystallography, will be vital to exploit the druggability of this target class [43].
