Cyclic Nucleotide Gated Channel Beta 1 (CNGb1)

The human and bovine rod photoreceptor cGMP-gated cation channel consists of 2 subunits: alpha (63 kD) and beta (240 kD). The protein coding region of the human CNGB1 gene consists of 12 exons spanning approximately 11 kb with sequence identical to that of the cDNA clones. Sequence analysis of cDNA clones encoding human CNCG3L revealed an open reading frame predicting a protein of 299 amino acids (approximately 32 kD), half the size of the bovine gamma subunit. Within the first 31 amino acids, they found 90% identity between the human and bovine sequences, and only 60% homology was found throughout the remainder of the protein sequence. As in bovine gamma, the predicted isoelectric point of the human protein is very acidic despite the absence of the bovine C-terminal glutamic acid-rich domain.