Hi Yanhe,
Our mmCIF expert Greg is away right now, but this was discussed in chimerax-users recently, see:

<https://mail.cgl.ucsf.edu/mailman/archives/search?mlist=chimerax-users%40cgl.ucsf.edu&q=entity_poly.pdbx_strand_id>

From the first message in those search results, our expert Greg said this should not happen if the full sequence information is associated with the structure.  It can be added using the ChimeraX daily build (feature added after 1.8 release) by method (B) described in his message.  That approach is also documented here:
<https://rbvi.ucsf.edu/chimerax/docs/user/commands/sequence.html#update>

I don't know anything about Pymol so I can't answer that part of your question.

I hope this helps,
Elaine
-----
Elaine C. Meng, Ph.D.                       
UCSF Chimera(X) team
Resource for Biocomputing, Visualization, and Informatics
Department of Pharmaceutical Chemistry
University of California, San Francisco


> On Aug 7, 2024, at 1:47 PM, Yanhe Zhao via ChimeraX-users <chimerax-users@cgl.ucsf.edu> wrote:
>
> Dear ChimeraX community and developer,
>
> I am trying to deposit my map with model.
>
> I save the model from pdb to cif in ChimeraX because of large amount of atoms, then got error as "Missing '_entity_poly.pdbx_strand_id' item.
>
> I tired to use pymol to open my pdb and save it as cif by 'Export Molecule', in which I just use the default options.
> I checked the saved cif in ChimeraX, which is weird since it couldn't be show in cartoon style.
>
> Is there any easy to handle this in ChimeraX or any option should be used in the 'Export Molecule' in Pymol?
>
> Thanks and cheers,
> Yanhe