Verdict
Learn the endocannabinoid system first. Cannabinoid receptors are two parts of it, not a separate system. A label that says "ECS" covers more ground than one that says "CB1" or "CB2". If you have room for one topic, take the whole system.
What each term covers
Endocannabinoid system
The endocannabinoid system has three parts: receptors, endogenous ligands, and enzymes. The ligands are anandamide, reported in 1992, and 2-AG, reported in 1995. Both are lipids made on demand and broken down fast. FAAH degrades anandamide. MAGL degrades 2-AG. The system appears in brain, immune cells, gut, skin, and liver.
endocannabinoid system deficiency and disease
- Receptors: CB1, CB2, plus GPR55, TRPV1, PPAR-alpha
- Ligands: anandamide (AEA), 2-AG
- Enzymes: FAAH, MAGL, DAGL, NAPE-PLD
Cannabinoid receptors
CB1 was cloned in 1990. CB2 followed in 1993. Both are G-protein coupled receptors that signal through Gi/o. CB1 sits at high density in cortex, hippocampus, basal ganglia, and cerebellum. CB2 sits on immune cells and microglia. THC binds both. CBD binds both with low affinity and acts as a negative allosteric modulator at CB1.
Options
Option 1: Full ECS panel
Covers receptors, ligands, and enzymes. Fits work on endocannabinoid tone rather than single-target binding. Highest cost. Most data.
Option 2: CB1 and CB2 screen
Two targets. Faster turnaround. Fits work on THC potency and receptor affinity. Misses enzyme and ligand effects.
Option 3: Receptor panel with GPR55 and TRPV1
Adds two targets that CBD touches. Fits work on CBD rather than THC.
How to pick
Count the targets you need. Two targets means a receptor screen. Five or more means a full panel. Convenience pushes buyers toward two-target kits. The data gap shows up later.