Homologous desensitization occurs when a receptor decreases its response to a signalling molecule when that agonist is in high concentration. It is a process whereby after prolonged agonist exposure, the receptor is uncoupled from its signaling cascade, and thus the biological effect of receptor activation is attenuated.
Homologous desensitization should not be confused with heterologous desensitisation, which is a different process whereby repeated stimulation of a receptor by one agonist results in desensitivity to a range of other agonists.
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