Signal Transduction Pathway

Signal Transduction Pathway

process by which a signal on a cell’s surface is converted into a specific cellular response in a series of steps

Reception

first step of cell signaling

• detection of signal molecule coming from outside cell

Transduction

second step of cell signaling

• convert signal to a form that can bring about a cellular response

Response

third step of cell signaling

• specific cellular response to signal molecule

ligand

signal molecule

amplify

signal transduction pathways have the power to ? the binding of a single ligand into MANY responses

G Protein-Coupled Receptors

Cell-surface transmembrane receptors that work with G proteins

• G proteins bind energy-rich GTP (similar to ATP)

  • all G proteins are similar in structure

  • GPCR systems are extremely widespread and diverse in function

Receptor Tyrosine Kinase

Membrane receptors that transfer phosphate groups from ATP to another protein

• can trigger multiple signal transduction pathways at once

• abnormal RTK function is associated with cancer

Ligand-Gated Ion Channel

gate that opens and closes when the receptor changes shape

• when a signal molecule binds as a ligand, gate allows specific ions (e.g. Na⁺ or Ca²⁺) through channel in receptor

cyclic adenosine monophosphate

secondary messenger that comes from ATP