Figure 1. PCR primer design strategy

PCR Primers were designed to target regions of high cross-species homology for the M1 receptor but low cross-subtype homology for other chick muscarinic receptors. A: Schematic diagram of the sequence alignment between all identified M1 mRNA sequences. Regions with a high degree of sequence homology between these M1 sequences were identified (in boxes), and the two primer sets (M1a and M1b) were designed to target sites within these areas. B: The regions with a high degree of sequence homology between the chick mAChR subtype sequences (M2 to M5) are highlighted (in boxes). Primers were designed outside these regions to avoid mis-priming of these receptor sequences.