A signaling molecule (ligand) binds to a specific receptor on the cell surface or inside the cell.
The receptor triggers a relay of intracellular molecules, often called a signaling cascade (e.g., using G-proteins or kinases). signaling
The signal finally triggers a specific cellular activity, such as gene expression or enzyme activation. Types of Signaling: Autocrine: A cell targets itself. A signaling molecule (ligand) binds to a specific