Final answer:
Glutamate receptors are primarily located on postsynaptic neurons, which are responsible for the synaptic transmission that activates the neurons following glutamate binding.
Step-by-step explanation:
Glutamate receptor sites are primarily found in postsynaptic neurons, where they play an essential role in synaptic transmission. When glutamate is released from the presynaptic neuron, it crosses the synaptic cleft and binds to these receptors on the postsynaptic neuron. This binding triggers a conformational change that typically results in an increased flow of positively charged ions into the postsynaptic neuron, leading to excitation or depolarization of that neuron.
Glutamate receptors can be classified into two types: ionotropic receptors, including NMDA, AMPA, and kainate receptors, and metabotropic glutamate receptors (mGluRs). The ionotropic receptors directly control the opening of ion channels and are responsible for the fast excitatory synaptic transmission in the CNS. NMDA receptors are particularly known for their role in synaptic plasticity and learning, as they have a voltage-dependent ion channel that is blocked by magnesium ions at resting membrane potential but allows calcium influx following depolarization.
Although astrocytes and microglia are involved in the modulation of synaptic activity and plasticity through gliotransmission, the direct binding sites for glutamate after its release are found on the postsynaptic neurons.