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1- When bacteria are consumed by macrophages, the macrophages give off chemokine

ID: 176171 • Letter: 1

Question

1-    When bacteria are consumed by macrophages, the macrophages give off chemokines to recruit other immune cells. The chemokines serve as ligands for G-protein coupled receptors. Which of the following is NOT true of G-PCRs?

a- GPCRs require GTP for pathway activation.

b- GPCRs bind the ligand extra-cellularly and undergo an allosteric change.

c- The receptor is a G-protein

d- The G-protein is lipid anchored.

2- In some autoimmune disorders, chemokines bind GPCRs to direct immune cells to sites that are not actually foreign invaders. Which of the following might be a treatment for such disorders?

a- A non-hydrolyzable GTP analog

b- A dominant-negative receptor

c- A molecule that constitutively blocks the ligand-binding site.

d- An inhibitor of arrestin.

a- GPCRs require GTP for pathway activation.

b- GPCRs bind the ligand extra-cellularly and undergo an allosteric change.

c- The receptor is a G-protein

d- The G-protein is lipid anchored.

Explanation / Answer

1. G protein–coupled receptors are found only in eukaryotes, including yeast, choanoflagellates and animals

d- The G-protein is lipid anchored.

2. d- An inhibitor of arrestin.