Question

. Consider the apical location of a particular protein expressed in epithelial cells, illustrated in Figure A. Which type of defect described below is the most likely to cause the redistribution of that protein around the entire cell, shown in Figure B?

(A)
protein A
apical plasma (B) membrane
tight junction
lateral plasma membrane
basal plasma membrane
basal lamina
(a) (b) (c) (d)
a nonfunctional protein glycosylase
the deletion of a junctional protein
the truncation of a protein found in the extracellular matrix a nonfunctional flippase

Answer 1

The most likely cause for the redistribution of an apically-located protein around the entire cell is a defect in the tight junctions, likely due to the deletion of a junctional protein.

Step-by-step explanation:

The redistribution of a particular protein around the entire cell, which was initially located at the apical surface of epithelial cells, is likely due to a defect in the tight junctions. Tight junctions are critical for maintaining the polarity of epithelial cells, separating the apical and basal compartments, and preventing the movement of proteins and other substances between these domains. A deletion of a junctional protein integral to the structure and function of these tight junctions could lead to a loss of cell polarity and a redistribution of the protein around the cell, as noted in the question. The other options, such as a nonfunctional protein glycosylase, the truncation of a protein found in the extracellular matrix, or a nonfunctional flippase, are less likely to directly contribute to this specific change in protein distribution.