Apo B48 & Apo B100 is synthesized from the same mRNA; the difference between them is due to
**Core Concept**
Apo B48 and Apo B100 are two isoforms of apolipoprotein B, a protein essential for the transport and metabolism of lipids in the body. They are synthesized from the same mRNA, but differ in their processing and translation.
**Why the Correct Answer is Right**
Apo B48 is produced through a unique mechanism involving alternative RNA splicing, where a specific exon is skipped during the translation process. In contrast, Apo B100 is translated from the full-length mRNA, resulting in a longer protein. This difference in processing is crucial for their distinct functions in lipid metabolism.
**Why Each Wrong Option is Incorrect**
**Option A:** Cleavage by a specific protease is not the primary mechanism for the difference between Apo B48 and Apo B100.
**Option B:** The difference is not due to post-translational modifications, as both isoforms undergo similar modifications after translation.
**Option C:** The difference is not solely due to differences in mRNA stability, as both isoforms are synthesized from the same mRNA.
**Clinical Pearl / High-Yield Fact**
Apo B100 is the primary apolipoprotein component of low-density lipoproteins (LDL), often referred to as "bad cholesterol." Elevated levels of Apo B100 are associated with increased risk of atherosclerotic cardiovascular disease.
**Correct Answer: D. Alternative RNA splicing**