Figure 4.

Cytosolic recognition of mislocalized proteins. (A) Targeting signals (or transmembrane domains) can be recognized by dedicated cytosolic factors that recruit ubiquitination machinery to mediate substrate ubiquitination. These substrates are then degraded by proteasomes. (B) Schematic depiction of the concept that different cytosolic factors, all of which recognize exposed hydrophobicity, are tuned to different lengths and degrees of hydrophobic domains. Biochemical analyses suggest that there is substantial overlap in what is recognized.