I would like to highlight a hole in a protein -the exit tunnel of a ribosome, to be more specific. I tried the command shape tube in order to draw three tubes passing through three residues, but the result doesn't suit at best my need and expectations.

Is possible to draw a circle, passing through three points -or residues-?

Do you have any suggestions?

Thank you for your attention.

Have a great week end.

Greetings,

Andrea