Alignment of the PEST region of CFTR. The top line is the human PEST sequence used in the study. A cross-species alignment of the CFTR amino acid sequences from residues 716 to 734 of the human CFTR shows great conservation in the region. Discrepancies with the human CFTR are noted in italics. Significant PEST residues are noted with asteriks. The PEST region is in the Regulatory (R) domain of CFTR. Partial sequences were found using the PubMed http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed. Accession number and references for each species are as follows: Human (P13569; ), Rhesus (AAC14012; ), Macaque (AAF80467; unpublished; direct submission), Baboon (AAD46907; unpublished; direct submission), Rabbit (Q00554; ), Sheep (Q00555; ), Bovine (P35071; ), Rat (1901178A; unpublished; direct submission), Mouse (P26361; ). The lower panel shows a model of CFTR and location of the predicted PEST region in the R-domain (R). The cylinders represent predicted transmembrane domains and the squares represent the nucleotide-binding domains (NBD1 and NBD2).