Identification of hepatic copper-binding proteins from tilapia by column chromatography with proteomic approaches.
Although copper is an essential element, it shows cytotoxic effects when present in excessive amounts with the production of hydroxyl radicals, which can damage phospholipids and enzymes. This necessitates a tight cellular control mechanism for copper homeostasis including its uptake and removal. The high copper contents in the liver of tilapia make this fish a suitable model for the study of copper binding proteins (CBPs). The liver was dissected from tilapia injected with Cu(2+) and cytosolic fractions were separated by using Superdex 75 column chromatography followed by atomic absorption spectrometry. Fractions in two major peaks containing CBPs were analyzed by using differential proteomic approaches, and loaded on a Cu chelating ion-immobilized affinity column (Cu-IMAC). Of the 113 differentially expressed proteins in these two peaks, 28 proteins were found to have copper binding ability, including well-characterized CBPs, such as copper transporter ATP7A and metallothionein. The networks of CBPs built up by Ingenuity Pathway Analysis (IPA) would help us to understand the transportation pathway and function of CBPs, which were related to free radical scavenging, cellular development and lipid metabolism. In addition, our results suggest that Cu(2+) would compete with Fe(2+) and Ca(2+) in binding with some target proteins, such as ferritin, transferrin, and calmodulin.
School of Life Sciences, The Chinese University of Hong Kong, Sha Tin, N.T., Hong Kong Special Administrative Region, China.
Dongshi
D
Chen
King Ming
KM
Chan
D000818:Animals; D002846:Chromatography, Affinity; D003300:Copper / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D029941:Fish Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D005786:Gene Expression Regulation; D008099:Liver / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D040901:Proteomics; D013054:Spectrophotometry, Atomic; D017210:Tilapia / Q000235:genetics / Q000378:metabolism*
D029941:Fish Proteins; D003300:Copper