Screw-Cap Clamp Loader Proteins that Thread

Structures of the clamp loader–clamp complex reveal that nature uses machined parts in the form of a spiral scaffold (the clamp loader) to thread a circlet (the clamp) on a helix of DNA. The scaffold is then replaced by an interpretive copying machine, the polymerase, to eventually generate the replisome for DNA replication

Measurement of protein–ligand complex formation

Experimental approaches to detect, measure, and quantify protein–ligand binding, along with their theoretical bases, are described. A range of methods for detection of protein–ligand interactions is summarized. Specific protocols are provided for a nonequilibrium procedure pull-down assay, for an equilibrium direct binding method and its modification into a competition-based measurement and for steady-state measurements based on the effects of ligands on enzyme catalysis