Interestingly, this modulation is almost exclusively in striatopallidal MSNs due to differential Kir2 subunit expression in striatonigral and striatopallidal neurons. Kir2 channels are constructed from a family of at least four subunits (Kir2.1–2.4). Kir2.1 subunits have a higher affinity for binding PIP2, whereas Kir2.3 subunits have a significantly lower affinity. Using a serial dilution scRT-PCR strategy, Shen et al. showed that the Kir2.3 mRNA is roughly two-fold higher in striatopallidal than in striatonigral MSNs [27]. The consequence of this imbalanced is that channels with Kir2.3 subunits, such as in striatopallidal MSNs, are much more potently modulated by receptors coupled to PLC.
