Figure 13.
Steric shielding of the Nt-acetylated N-terminal residue of a subunit in a protein complex. Shown here is a part of the crystal structure, by the Barford laboratory, of a complex between the Hcn1 and Cut9 subunits of the S. pombe APC/C Ub ligase.247 In this structure, the Nt-acetylated N-terminal Met residue of Hcn1 is enclosed within a chamber formed by the Cut9 subunit, including its interface with the other Cut9 subunit in the heterotetramer of Hcn1 and Cut9. N-terminal region of Hcn1 is shown in cyan as a stick model, and Cut9 is depicted as a cut-out surface representation, to show the chamber's interior.247 [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]