Final answer:
Proteins without a sorting signal remain in the cytosol of a eukaryotic cell, as they are not directed to other organelles or the plasma membrane.
Step-by-step explanation:
Proteins that lack a sorting signal remain as permanent residents of the cytosol part of a eukaryotic cell. These proteins, synthesized in the cytoplasm, do not contain oligopeptide traffic signals that would direct them to other organelles or to the plasma membrane. Instead, without these signals, they stay within the cytosol after translation. The cytosol is the semi-fluid, cytoplasmic matrix where a majority of cellular activities take place, including certain metabolic pathways and protein synthesis.
Proteins destined for other specific locations in the cell, such as the nucleus, mitochondria, chloroplasts, endoplasmic reticulum (ER), Golgi apparatus, or lysosomes, possess specific sorting signals for targeting. For example, proteins intended for secretion or membrane insertion are synthesized in the rough endoplasmic reticulum (RER), modified in the Golgi apparatus, and packaged into vesicles for their intended destinations.