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Consider the apical location of a particular protein expressed in epithelial cells, illustrated in Figure Q11-49A. Which type of defect described below is the most likely to cause the redistribution of that protein around the entire cell, shown in Figure Q11-49B?

(a) a nonfunctional protein glycosylase
(b) the deletion of a junctional protein
(c) the truncation of a protein found in the extracellular matrix
(d) a nonfunctional flippase

1 Answer

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Final answer:

The deletion of a junctional protein is the most likely to cause the redistribution of the protein expressed in epithelial cells around the entire cell, as junctional proteins are essential in maintaining the polarized distribution of proteins. the correct option is b) the deletion of a junctional protein.

Step-by-step explanation:

The apical location of a particular protein:

The most likely cause for the redistribution of the protein around the entire cell is (b) the deletion of a junctional protein. Epithelial cells maintain their polarity, which includes having different proteins on their apical and basal surfaces, often through the use of junctional proteins. When junctional proteins are disrupted, the selective distribution of membrane proteins is affected, leading to the mislocalization of proteins such as the one described.

Issues with protein glycosylation, truncation of extracellular matrix proteins, or flippase dysfunction can all lead to various cellular abnormalities, but they are less likely to directly cause the redistribution of apical proteins around the cell compared to the loss of junctional proteins. Understanding membrane protein trafficking and polarity is essential for grasping how cellular functions are compartmentalized, particularly in epithelial tissue.

User Andrew Kozak
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