You are studying a transporter found only in the apical plas…

You are studying a transporter found only in the apical plasma membrane of epithelial cells. You treat the epithelial cells with a synthetic peptide that is similar to the extracellular domain of a tight junction protein. The transporter is now found in both the apical and basolateral domains of the plasma membrane. What is the most likely mechanism by which the peptide disturbs the localization of the transporter?

As discussed in this section, mutations in the LDL receptor…

As discussed in this section, mutations in the LDL receptor can cause familial hypercholesterolemia. However, mutations in apolipoprotein B100 have also been discovered that cause hypercholesterolemia. For example, mutation of arginine-3500 to glutamine (R3500Q) in apolipoprotein B100 was one of the first such mutations. Which of the following is an appropriate hypothesis for how apolipoprotein B100 mutations cause hypercholesterolemia?