Question

Which of the following is true about G-PROTEIN COUPLED RECEPTOR and RECEPTOR TYROSINE KINASES?

1) The binding site for the signaling molecule is located on the extracellular side of the cell
2) They interact directly with G protein
3) They catalyze the transfer of a phosphate group to the receptor
4) The binding of the signaling molecule forms a dimer
5) The binding of the signaling molecule allows ions to flow through a channel in the receptor
6) The receptor is located in the plasma membrane

Answer 1

The binding site for signaling molecules of both G-protein coupled receptors and receptor tyrosine kinases is on the extracellular side. Receptor tyrosine kinases also catalyze the transfer of a phosphate group upon ligand binding and form dimers, while both receptors are located within the plasma membrane.

Step-by-step explanation:

Among the options provided, certain features are true about G-protein coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs). Firstly, the binding site for the signaling molecule indeed is located on the extracellular side of the cell. In GPCRs, this binding leads to the activation of a G-protein on the intracellular side. For RTKs, the binding of a signaling molecule, such as a growth factor, facilitates dimerization, or pairing of two RTK molecules. Regarding RTKs, they are known for catalyzing the transfer of a phosphate group to specific tyrosine residues on the receptor itself, a process called autophosphorylation. This is a crucial step in signal transduction for RTKs. Lastly, both GPCRs and RTKs are indeed membrane proteins that span the plasma membrane, playing a key role in transmitting signals from outside the cell to the inside.