CHRNB3 (Cholinergic Receptor Nicotinic Beta 3 Subunit) is a protein that forms part of the nicotinic acetylcholine receptor, which plays a key role in cholinergic neurotransmission. Variations in the CHRNB3 gene have been linked to nicotine dependence and related behavioral traits, suggesting its involvement in the brain’s addiction pathways and neural circuitry regulation.