1. Another Twist in Helix C and a Missing Pocket
Elizabeth J Goldsmith, Chung-I Chang 
Structure 
Volume 10, Issue 7, Pages (July 2002)
DOI: /S (02)

2. Figure 1 The Structure of PKA (PDB File 1ATP)
Highlighted in gray are the elements missing in the structure of PKB. The residues corresponding to helix B and C were present in the crystal but not the electron density. The activation loop, labeled A loop, is also disordered. The hydrophobic motif and Ser 474 not present in the construct crystallized.
Structure  , DOI: ( /S (02) )