For several editions, Anatomy & Physiology has featured a brief description of the structure and function of proteasomes in the cell. As several recent papers in Science, Nature, and other journals point out, understanding the proteasome is critical to understanding how the cell handles protein—a "big idea" in the A&P course.
For example, the drug bortezomib (Velcade) is a proteasome inhibitor used to treat some adults with multiple myeloma.
So given the central role of the proteosome, why is this vitally important organelle left out of most A&P textbooks? Really, I'm asking. Because I can't think of a good reason.
Besides its emerging role in understanding major diseases and therapeutic strategies, the proteosome gives students a more complete picture of the cell as a "protein factory." It helps integrate the whole protein synthesize story with the basic concepts of amino acids and protein folding learned earlier in the course. Not to mention the homeostasis of amino acid balance in cells.
The proteasome story can be told simply, so there's no reason to leave it out for the reason that "it's just too much detail" for a beginning student to handle. Check out this resource intended for high-school students: The Proteasome.
Anatomy & Physiology features a short, illustrated description of the ubiquitin-proteasome system that easily integrates with the bigger picture of protein handling in the cell. It's on page 85 of the new 9th edition. Now you know why I included it!