When stimulated by binding to bacterial products, the fMet-Leu-Phe (fMLF) receptor triggers multiple responses by phagocytes, including migration and induction of antimicrobial activities. Most of these responses are activated by small GTPases of the Rac and Rho families that are indirectly activated by fMLF receptor stimulation. The fMLF receptor can initiate multiple downstream signaling pathways because:
A) It couples to a heterotrimeric G protein that has $\alpha$ and $\beta$$\gamma$ subunits with independent activities.
B) It couples directly to two different guanine nucleotide exchange factors (GEFs).
C) It binds to Rac, Rho, and cdc42 directly.
D) It promotes fusion of phagosomes with lysosomes, initiating multiple signals.
E) It induces assembly of multiple enzymes from individual cytosolic components.

Question

Quizplus · Accepted Answer

The fMLF receptor can initiate multiple downstream signaling pathways because it couples to a heterotrimeric G protein, which has alpha (α) and beta-gamma (βγ) subunits with independent activities. This allows the receptor to activate different signaling cascades through the activation of these distinct G protein subunits.

When Stimulated by Binding to Bacterial Products, the FMet-Leu-Phe (FMLF) α\alphaα

When Stimulated by Binding to Bacterial Products, the FMet-Leu-Phe (FMLF) $\alpha$