Figure 6: Schematic representation of the length requirement for internal and terminal initiation regions.
From: Rad23 escapes degradation because it lacks a proteasome initiation region
Substrates shown contained a UbL domain bound to the proteasome in an arbitrary position attached to either a dihydrofolate reductase (DHFR) domain followed by an initiation region (blue) or an initiation region (red and blue) followed by a DHFR domain. Length requirements for an internal initiation region (red and blue) were at least twice that for a terminal initiation region (blue). Light grey, proteasome caps; dark grey, proteasome core; circular arrows, ATPase subunits; scissors, proteolytic sites.
