Comparative Promoter Analysis of the Homologues Ceruloplasmin and Hephaestin
Ceruloplasmin and hephaestin are related ferroxidases, both thought to aid in iron homeostasis, but hephaestin is membrane-bound and ceruloplasmin circulates free in the blood. Studying the promoter regions of these molecules will give valuable insight into the different functions and expression patterns of these similar proteins. Specifically, the presence of particular transcription factor binding (TFB) sites will identify the tissues in which these genes are active and at what times. A bioinformatics approach will be used to identify and download promoter sequences of ceruloplasmin and hephaestin from different species. Since ceruloplasmin is not membrane-bound and is free to circulate throughout the blood, ceruloplasmin should be responsive to more conditions and have more TFB sites in its promoter than the gene for the membrane-bound hephaestin.
Iron is an important trace element which can also be toxic under certain circumstances. Iron is involved in several important physiological processes such as DNA synthesis, respiration and oxygen transport (Collins and Hu 2007). The regulation of iron is essential, but when iron homeostasis is disrupted, the result can lead to iron deficiency or iron overload. Iron deficiency can stop cell growth and can also lead to cellular death. Iron overload is also a problem because free iron readily participates in redox reactions in cells, which leads to oxidative damage (Collins 2006). Another element of importance is copper. The metal copper is transported in to the cell via CTR1, a copper transporter, which helps to regulate copper and avoid toxicity. In some cases, copper can bind to certain compounds that are redox reactive, which can influence certain processes in the cell including apoptosis (Das et al., 2007). The ceruloplasmin and hephaestin proteins are homologous...