The black crosses on the secondary structure diagrams indicate where the
PDB and UniProt sequences differ.
Where there is more than one PDB model for a given UniProt sequence,
the models are ordered by: 1. decreasing order of similarity to the
UniProt sequence, 2. X-ray structures (in order of increasing
resolution), NMR structures, and theoretical models. Clicking on any
PDB code take you to the corresponding PDBsum page.