Which of the following turns off an RTK signaling pathway by shutting off the receptor?Group of answer choicesKinasesPhosphatasesGAPsGEFs

To determine which option turns off an RTK (Receptor Tyrosine Kinase) signaling pathway by shutting off the receptor, let’s analyze each choice:

1. Kinases: These are enzymes that add phosphate groups to proteins, typically activating their function. They often serve to propagate a signaling cascade rather than shut it down.

2. Phosphatases: These enzymes remove phosphate groups from proteins. In the context of RTK signaling, phosphatases can deactivate receptors by dephosphorylating them, effectively turning off the signaling pathway.

3. GAPs (GTPase-activating proteins): GAPs promote the inactivation of GTP-binding proteins, but they are not directly responsible for shutting off RTK receptors.

4. GEFs (guanine exchange factors): These proteins activate GTP-binding proteins by facilitating the exchange of GDP for GTP. They do not serve a role in turning off receptor activity.

Final Answer

The correct choice is Phosphatases, as they deactivate RTK signaling pathways by removing phosphate groups from the receptors, thereby shutting them off.