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. 2013 Jan 17;288(10):7215–7229. doi: 10.1074/jbc.M112.443226

FIGURE 1.

FIGURE 1.

CNGA3-predicted protein structure and mRNA expression in cochlear outer hair cells and inner hair cells. A, shown is a diagram illustrating the predicted structure of the CNGA3 protein (GenBankTM EDL99244, rat). The cytoplasmic amino terminus sequence is encircled in a schematic depiction of CNGA3 with S1-S6 transmembrane regions and S4 hatched representing the voltage sensor and CNBD referring to the cyclic nucleotide binding domain. B, shown is PCR amplification of a 242-bp cDNA product corresponding to the amino terminus of rat CNGA3, from the analysis of pooled, singly isolated rat cochlear outer hair cells (OHC) and inner hair cells (IHC). The primers were designed to target the CNGA3 sequence expressed in a subset of rat olfactory sensory neurons (16) (GenBankTM AJ272428) with an identity to human cone photoreceptor CNGA3 (NP_001073347) and trout saccular hair cell CNGA3–2 (HQ542178). The amplification product yielded rat CNGA3 sequence with 99% nucleotide identity for cochlear outer hair cell and 98% nucleotide identity for inner hair cells to rat AJ272428. Lanes S, 1-kb standards; lanes OHC and IHC, CNGA3 242-bp amino terminus products amplified from rat cochlear outer and inner hair cells, respectively, arrow; lane B, negative control in which cDNA was omitted. C, shown is alignment (with OMIGA 2.0) of the amino terminus amino acids of rat organ of Corti CNGA3 (EDL99244) used as bait (RAT CNGA3-N, second line) in yeast two-hybrid protocols aligned with human CNGA3 (HUM CNGA3-N, first line, NP_001073347) and trout saccular hair cell CNGA3–2 (THC CNGA3-N, third line, AER38241). CNGA3 amino termini display partial EF hand Ca2+ binding domains (17), DRDLDQ, aa 23–28, for rat organ of Corti sequence with comparable motifs appearing in the calcium-binding protein Cab45 (Q91ZS3), cadherin 23 (58), and EDH4 (36, NP_647540). In addition, there is a PDZ domain NGLG aa 31–34 (compare with piccolo, EDL99465). The amino terminus of trout saccular hair cell CNGA3–2 variant (third line) indicates identity to both human (first line) and rat CNGA3 (second line) sequences.