PARP1 and HPF1 team up to flag down DNA-repair machinery

The enzymatic activity of PARP1—which adds chains of (poly-ADP)-ribose (PAR) to proteins—initiates DNA repair by leading to more-accessible chromatin and recruitment of PAR-dependent DNA-repair proteins. New work shows that these PARP1-catalysed functions are redirected by the auxiliary factor HPF1 in cells.