Question

Signaling proteins that dock onto an RTK can be activated in several ways. Each one of the following statements describe such an activation mechanism EXCEPT: A. A docked signaling protein may be activated by proximity to its target. B. A docked signaling protein may be activated by tyrosine phosphorylation. C. A docked signaling protein may be activated by a conformational change. D. A docked signaling protein may be activated by release from the receptor.

1) A docked signaling protein may be activated by proximity to its target.
2) A docked signaling protein may be activated by tyrosine phosphorylation.
3) A docked signaling protein may be activated by a conformational change.
4) A docked signaling protein may be activated by release from the receptor.

Answer 1

Signaling proteins docked on RTKs can be activated by proximity, tyrosine phosphorylation, or conformational changes, but activation by release from the receptor is not a listed mechanism.

Step-by-step explanation:

The question concerns the various mechanisms by which signaling proteins that dock onto a Receptor Tyrosine Kinase (RTK) can be activated.

The correct activation mechanisms for a docked signaling protein include being activated by proximity to its target, by tyrosine phosphorylation, and by a conformational change. However, signaling proteins activated by release from the receptor is not listed as an activation mechanism in the provided information, making it the EXCEPT option.

RTKs function by autophosphorylating tyrosine residues on their intracellular domains upon ligand binding and dimerization, triggering downstream signaling pathways including a phosphorylation cascade, ultimately affecting gene regulation.