Abeysinghe, S.S.Baker, M. L.Chiu, W.Ju, T.2015-02-232015-02-2320101467-8659https://doi.org/10.1111/j.1467-8659.2010.01813.xIn this paper, we study a registration problem that is motivated by a practical biology problem - fitting protein structures to low-re solution density maps. We consider registration between two sets of lines features (e.g., helices in the proteins) that have undergone not a single, but multiple isometric transformations (e.g., hinge-motions). The problem is further complicated by the presence of symmetry in each set. We formulate the problem as a clique-finding problem in a product graph, and propose a heuristic solution that includes a fast clique-finding algorithm unique to the structure of this graph. When tested on a suite of real protein structures, the algorithm achieved high accuracy even for very large inputs containing hundreds of helices.10.1111/j.1467-8659.2010.01813.x2243-2252