The form of apolipoprotein B (Apo-B) produced by the intestine is shorter than the Apo-B produced by the liver. The intestine produces a smaller protein by
A) proteolytic cleavage of the forming polypeptide chain.
B) a base alteration that changes a codon for glutamine to a termination codon.
C) shortening the mRNA from the 3' end after translation.
D) including fewer exons in the mRNA by alternative splicing.

Question

Quizplus · Accepted Answer

A base alteration that changes a codon for glutamine to a termination codon would result in a shorter protein as the translation would be terminated prematurely. This is known as a nonsense mutation. Therefore, the intestine likely produces a shorter Apo-B protein due to a nonsense mutation that introduces a premature stop codon, resulting in a truncated protein.

The Form of Apolipoprotein B (Apo-B) Produced by the Intestine