Local symmetry operators for refinement



We have an asymmetric particle containing multiple copies of the same sub-complex. Can we impose local symmetry during refinement in cryosparc similar to what has been implemented in relion? If not, is this on the to-do list for future upgrades?


Hi @jochen,

We are currently working on implementing support for non-standard symmetry in cryoSPARC. The first case we are working on is supporting multiple copies of an identical subvolume located at arbitrary locations on the volume, e.g. non-crystallographic symmetry. The second case will allow for the local refinement of symmetric units that are flexible with respect to one another.



Is there a reason local symmetry is better than localized refinement and expansion?

Using both localrec or my subparticles.py from pyem you can provide multiple target coordinates and align any number of subparticles at arbitrary locations.


Hi @DanielAsarnow, I think local symmetry is better only in the instance where your subunits are small (too small to reliably align on their own) and the non-crystal symmetry is rigid (i.e. no flex between subunits). I’m not sure how common that is though!