You are examining the characteristics of a cell line isolated from tumor tissue and comparing it to normal tissue cells. You find that addition of a particular growth factor to the normal cells results in increased gluconeogenesis, but that in the tumorderived cells this effect is absent. You suspect that there is a defect in receptor-mediated signaling and surmise that there is altered G-protein-coupled activity in the tumor cells. Which type of G-protein is likely to be defective? A) G₁₂ B) G_i C) G_q D) G_s

Question

Quizplus · Accepted Answer

G_s is typically involved in stimulating adenylate cyclase, which increases cAMP levels and can lead to increased gluconeogenesis. If the tumor cells do not respond to the growth factor with increased gluconeogenesis, it suggests a defect in the G_s protein pathway.

You Are Examining the Characteristics of a Cell Line Isolated