**Core Concept**
Integral proteins are transmembrane proteins that span the entire cell membrane, exposing parts of their polypeptide chain on both the extracellular and intracellular sides. They are embedded within the lipid bilayer and play crucial roles in various cellular processes, including transport, signaling, and cell-cell interactions.

**Why the Correct Answer is Right**
Integral proteins are typically characterized by their hydrophobic transmembrane domains, which interact with the lipid bilayer. They are often covalently linked to the membrane through lipid anchors or palmitoylation. In contrast, peripheral proteins are loosely associated with the membrane and can be removed by mild treatments such as high salt concentrations or detergents.

**Why Each Wrong Option is Incorrect**
**Option A:** This is a placeholder for an incorrect option. Assuming it's an integral protein, it would be incorrect because the question asks for a non-integral protein.
**Option B:** This option might be a peripheral protein or another type of protein that is not integral. However, without more information, it's difficult to determine why it's incorrect.
**Option C:** This option might be a type of protein that is loosely associated with the membrane, such as a peripheral protein. However, it's not a definitive reason why it's incorrect.

**Clinical Pearl / High-Yield Fact**
It's essential to distinguish between integral and peripheral proteins when studying cell membrane structure and function. Integral proteins are typically involved in transport and signaling processes, while peripheral proteins often play roles in cell-cell interactions and adhesion.

**Correct Answer: D.**