Hi Andrea, If the pixel size is not defined in the header of the .mrc file if your EM map, chimera will use a default 1A/px. You can set correct pixel size using volume command with voxelSize option. For instance, if the target EM map is volume #1 and pixel size 1.5A, use volume #1 voxelSize 1.5 Best. Oleksiy

On 21 Jul 2020, at 13:14, Andrea Dallapè <andrea.dallape@unitn.it> wrote:

Hi,

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 _______________________________________________ ChimeraX-users mailing list ChimeraX-users@cgl.ucsf.edu Manage subscription: https://www.rbvi.ucsf.edu/mailman/listinfo/chimerax-users

Dr Oleksiy Kovtun Research Fellow Briggs group MRC Laboratory of Molecular Biology Francis Crick Avenue Cambridge CB2 0QH UK Tel: + 44 1223 267551 Email: okovtun@mrc-lmb.cam.ac.uk