Across cell populations, expression of nAChR genes exhibited two prominent correlation blocks, each containing genes that encode subunits of known heteromeric α/β channels (Zoli et al., 2015)(Figure 4A). For example, expression of Chrna3 and Chrnb4 (known to form functional receptors) was positively correlated across a large range (from 0.01 to 100 transcripts per 100K) (Figure 4B). Expression of other gene pairs encoding heteromeric receptors (Chrna6/Chrnb3 and Chrna4/Chrnb2) was also well correlated, whereas Chrnb1 and Chrnb2 were not, consistent with a lack of β1/β2 channels in brain (Figure 4B). These correlations match prominent subunit combinations associated at a protein level, suggesting nAChR composition is achieved in part by cell-type-specific patterns of RNA expression.
