Phylogeny of the Epithelial Sodium (ENaC) family
The epithelial sodium channel (ENaC) family are membrane proteins found in the epithelial cells of the respiratory, digestive, circulatory, urinary, sensory, reproductive, endocrine, nervous, lymphatic, and integumentary systems. The main function of ENaC is to maintain water and sodium homeostasis. Considering that the ENaC family members known to date (25 proteins in total according to TCDB.org) are from metazoa with no recognizable homologues in other eukaryotes or bacteria, we tried to find out whether or not there are other eukaryotic, microbial, and non-metazoan eukaryotic homologues for this channel, and if so, we would try to produce a phylogeny with the organisms that were found. Knowing that ENaC has implications in some lung diseases such as pneumonia and bronchitis, we will use this study of the evolution of this family of channels to understand and explain how this family of channels functions and what its biological role is in different organisms. We will work with database and programs such as Transport Classification Protein Database (TCDB.orf & Saier, et al. 2009), Biology WorkBench (workbench.sdsc.edu/) and InterPro (Mulder, et al. 2007) to find eukaryotic and microbial homologues organisms and to learn about their characteristics in relationship to this family of channels. Other programs like Proteins Sequence Parsimony Method (ProtPars) (Felsenstein, 1997), ClustalW (Thompson, et al. 1994), and MotifNetwork (Tilson, et al. 2007) will be helpful in order to produce the phylogeny and the evolutionary domain network in order to capture the horizontal as well as the vertical dimensions of the evolution of this family of channels.