I have an EM map -from a cryoET experiment- and I would like to use ChimeraX in order to fit the protein -the ribosome, in this case- in such EM map.

I don't understand why the PDB of the ribosome I open in ChimeraX is far bigger than the EM map I have, and I don't really know how to resize them in order to have a fittable model.

Could you suggest me a solution?

Thank you for your help and attention,

Andrea