Concept explainers
To examine: Whether the statement “given the numerous processes inside cells that are regulated by changes in Ca+2 concentration, it seems likely that Ca+2-dependent cell-cell adhesions are also regulated by changes in Ca+2 concentration” is true or false.
Introduction:
Cell-cell adhesions play an important role in maintaining the architecture of various tissues. The homophilic and heterophilic adhesion of cells is mediated by many cell-surface proteins (CAMs). CAMs are classified into five categories- cadherins, immunoglobulins, mucins, integrins, and selectins. Out of these, cadherin and selectin based cell adhesions depend on Ca+2 concentration.
Answer to Problem 1P
Correct answer: The statement is false.
Explanation of Solution
The regulation of various cell-cell interactions and processes are mediated by changes in Ca+2 concentration through Ca+2 signaling pathways. Cell surface proteins (CAMs) contribute in cell-cell adhesions. Cadherins come under Ca+2-dependent CAMs. The N-terminal extracellular domain is the site for binding of Ca+2 and thus, adhesion of cells. The removal of Ca+2 from extracellular medium dissociates the cells causing cadherins to mediate cell-cell adhesion. The cell-cell adhesion is not regulated by Ca+2 concentration changes as cells cannot control Ca+2 concentration in their environment. Hence, the statement is false.
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Chapter 19 Solutions
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