What distinguishes soluble proteins from integral membrane proteins?

The distinction between soluble proteins and integral membrane proteins is primarily based on their final location within the cell. Soluble proteins are typically found floating freely in the cytoplasm or located within organelles such as the nucleus or mitochondria. In contrast, integral membrane proteins are embedded within the lipid bilayer of cellular membranes, where they play crucial roles in various functions such as signaling, transport, and maintaining cell structure.

While signal sequences and post-translational modifications play important roles in the targeting and function of proteins, they do not solely define the difference between soluble and integral membrane proteins. For instance, both types of proteins can have signal sequences that guide their localization, and both can undergo various post-translational modifications, influencing their stability, activity, and interactions.

Focusing on the final cellular location provides the clearest criterion to differentiate between the two categories. Thus, the final location being the distinguishing factor highlights the functional and structural characteristics that set soluble proteins apart from integral membrane proteins.