Answer:
Receptors
Step-by-step explanation:
The cell membrane has receptors integrated or embedded into to it known as Membrane receptors or trans-membrane receptors . Membrane receptors are specialized proteins and act in cell signalling by receiving extracellular molecules by binding to them.
In multi-cellular organisms cell signalling allows speciation o groups of cells and when the signal is released the membrane receptors are the ones that will receive it.