Dear ChimeraX team,

Structure files in .cif format that are generated by ChimeraX are unfortunately not suitable for deposition to the PDB. This is due to lack of the column _entity_poly.pdbx_strand_id in the header. The column is usually found in the header in this table and contains the chain Identifier (i.e ‘A’ for chain A):

loop_

_entity_poly.entity_id

_entity_poly.nstd_monomer

_entity_poly.type

_entity_poly.pdbx_seq_one_letter_code_can

Since ChimeraX does an excellent at converting PDBs to mCIFs otherwise, would it be possible to have ChimeraX include this column in the header of mmCIF files?  This would greatly help to facilitate the tiresome process of depositing models to the PDB.

Many thanks in advance,

Best,

Matthias