This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Enzymes, Subject name: Biochemistry
[{'content': 'Extracellular binding domain for the ligand is present in all types of receptor except \nSelect and explain. \nA. G-protein, B. Enzyme linked, C. Transcription factors, D. None', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Cell surface receptors (membrane receptors, transmembrane receptors) are receptors at the surface of a cell (built into its cell membrane) that act in cell signaling by receiving (binding to) extracellular molecules. They are specialized integral membrane proteins that allow communication between the cell and the outside world. The extracellular molecules may be hormones, neurotransmitters, cytokines, growth factors, cell adhesion molecules, or nutrients; they react with the receptor to induce changes in the metabolism and activity of a cell. In the process of signal transduction, ligand binding affects a cascading chemical change through the cell membrane.', 'role': 'assistant'}]