Sequence homology and conservation of exon/intron boundaries. Alignment of human, mouse, killifish, and Fugu CFTR. The triangles mark approximate intron/exon boundaries. Domains of CFTR are as indicated: NBD = nucleotide-binding domain; R-domain = regulatory domain; TM = transmembrane segment. Horizontal lines linking transmembrane segments represent extracellular loops. Diamonds above the phosphorylated residues predict dibasic cAMP-dependent phosphorylation sites. Short horizontal bars marked with asterisks above exon 15 indicate glycosylation sites. In the background shading at each position, phosphorylation and glycosylation sites: black indicates perfect homology, dark grey three out of four, and light grey two out of four residues matching.
