The CB1 receptor is known to be part of the endocannabinoid system, which modulates activity in the brain, endocrine system, immune cells, and other parts of the body. Additionally, it is involved in stress responses and reproductive functions. The CB1 receptor is known to be a G protein-coupled receptor (GPCR), a type of receptor that is connected to heterotrimeric G proteins. G proteins are membrane proteins essential for transmitting extracellular signals into intracellular responses .