Various low-resolution experimental techniques have gained more and more popularity in obtaining structural information of large biomolecules.In order to interpret the low-resolution structural data properly,one may need to construct an atomic model of the biomolecule by fitting the data using computer simulations.Here we develop,to our knowledge,a new computational tool for such integrative modeling by taking the advantage of an efficient sampling technique called parallel cascade selection (PaCS) simulation.For given low-resolution structural data,this PaCS-Fit method converts it into a scoring function.After an initial simulation starting from a known structure of the biomolecule,the scoring function is used to pick conformations for next cycle of multiple independent simulations.