sentence: In the striatum , ChIs express the muscarinic acetylcholine receptors ( mAChRs ; M1 / M5 ) as well as various subtypes of nAChRs , composed mainly of α 4 , α 6 , α 7 , β 2 , and β 3 subunits , with the primary expression of the α 4 β 2 and α 6 β 2 receptors ( Quik and Wonnacott , 2011 ) .