Neurons communicate with one another through the release of neurotransmitters that bind to channels on the postsynaptic neuron. this is analogous to a lock and a key. in this example the lock is the while the key is the neurotransmitter.

The answer is receptor.

Explanation:

Neurotransmitters are chemical molecules released by the neurons to bridge the gap between and to be able to communicate. This is a process in which one side of the communication is the source of the neurotransmitters and the other is the receptor which is often used as a lock-key example. Since the neurotransmitter is the component which bridges the gap and in a sense unlocks the door, it is the key. The receptor is the part affected by the neurotransmitter which means that is the lock part of this example.

I hope this answer helps.

multiply it by 5 in order for you to understand i cant give an exact answer.