However, Nusser et al., (1998) provided additional evidence for the existence of receptors composed of α1α6βγ2 or α1α6βδ subunits by demonstrating separate as well as co-localization of α1 and α6 subunits in the cerebellum granule cells. This prompted us to place at least one receptor composed of α1α6βγ / α1α6βδ into a third list of “receptors that exist with high probability” (Category B). This list, in between “receptors unequivocally identified” (Category A) and “tentative receptors” (Category C), defines receptors for which additional evidence for their existence has been accumulated, but for which evidence seemed not strong enough to include them into the list of “identified receptors”.
