To identify genes encoding the receptors for the cytokines IL-2, IL-4, and IL-7, an siRNA screen is performed using purified T lymphocytes. To identify siRNAs that knock-down cytokine receptor expression, the T cells have been transfected with a construct that produces green fluorescent protein (GFP) when any one of these three cytokines is used to stimulate the cells. When the screen is completed, several different siRNAs have been identified that substantially reduce the T cells ability to respond to these cytokines as shown in Figure .
A correct statement regarding these data is:
A) siRNA-1 and siRNA-3 target subunits of the IL-2 receptor but siRNA-2 does not.
B) siRNA-2 targets a shared subunit of all three receptors, whereas siRNA-1 and siRNA-3 do not.
C) siRNA-3 targets a subunit of the IL-7 receptor, but the other two siRNAs do not.
D) siRNA-2 and siRNA-3 do not target a subunit of the IL-2 receptor.
E) siRNA-2 targets a subunit shared by all receptors in the hematopoietin receptor superfamily.

Question

To identify genes encoding the receptors for the cytokines IL-2, IL-4, and IL-7, an siRNA screen is performed using purified T lymphocytes. To identify siRNAs that knock-down cytokine receptor expression, the T cells have been transfected with a construct that produces green fluorescent protein (GFP) when any one of these three cytokines is used to stimulate the cells. When the screen is completed, several different siRNAs have been identified that substantially reduce the T cells ability to respond to these cytokines as shown in Figure .  
 A correct statement regarding these data is:
A) siRNA-1 and siRNA-3 target subunits of the IL-2 receptor but siRNA-2 does not. 
B) siRNA-2 targets a shared subunit of all three receptors, whereas siRNA-1 and siRNA-3 do not. 
C) siRNA-3 targets a subunit of the IL-7 receptor, but the other two siRNAs do not. 
D) siRNA-2 and siRNA-3 do not target a subunit of the IL-2 receptor. 
E) siRNA-2 targets a subunit shared by all receptors in the hematopoietin receptor superfamily.

Quizplus · Accepted Answer

The data presented in the figure indicate that siRNA-1 and siRNA-3 are specific to the IL-2 receptor, whereas siRNA-2 targets a shared subunit of all three receptors. The data do not provide information on whether siRNA-3 targets a subunit of the IL-7 receptor, and there is no indication that siRNA-2 targets a subunit shared by all receptors in the hematopoietin receptor superfamily. Therefore, the best choice is B.

To Identify Genes Encoding the Receptors for the Cytokines IL-2