What happens to proteins without a signal sequence in the secretory pathway?

Proteins without a signal sequence typically do not follow the pathway that leads to their secretion outside the cell or to specific compartments within the endomembrane system such as the endoplasmic reticulum (ER). Instead, they often end up being localized to the cytosol, where they perform their functions.

In the context of the secretory pathway, proteins that lack a signal sequence are generally not processed for secretion. They do not have the necessary cues for traveling through the secretory pathway to reach the cell membrane or undergo further processing in the Golgi apparatus. Instead, they may function within the cytosol or be directed to different organelles based on their inherent localization signals or characteristics outside of the classic secretory pathway.

The option indicating that these proteins are delivered to the cell membrane suggests a misunderstanding of the role of signal sequences. Typically, only proteins destined for secretion or membrane incorporation possess such sequences that guide them through the secretory pathway, while those without such sequences do not reach the cell membrane in the same context.