Structure and function of peroxisomal membrane proteins and assembly of the proteins into peroxisomal membranes

点击翻译按钮获取中文摘要

In this study, we investigated structure and function of several peroxisomal membrane proteins and characterized intracellular transport of one of the proteins to peroximal membranes. Following new evidences were obtained.1. In order to identify novel peroxisomal membrane proteins, several monoclonal antibodies against rat liver peroxisomal membranes were selected. Using one of the antibodies, a novel 57 kDa protein was identified. The protein is exposed to the cytosolic face of the peroxisomal membrane and the amount of the protein increased in paralleled with proliferation of peroxisomes.2. In order to examine structure of peroxisomal membrane proteins, a rat liver CDNA library in lambda gtll was screened by anti-peroxisomal membrane proteins antibodies. Positive cDNAs were selected and sequenced. One of them was identified as a novel 37 kDa protein. Other three clones were also identified as homologous proteins such as HMG-COA reductase, leucine aminopeptidase and subunit d of H^+-A … More TP synthase respectively.3. Biosynthesis and intracellular transport of a major peroxisomal membrane protein (69 kDa) were investigated in rat hepatoma H4-II-E cells. The cells were labelled with [ ^<35>S] methionine and chased for various periods of time. Subcellular distribution of the ^<35>S-69 kDa protein was analyzed by immunoprecipitation. The results suggest that the newly synthesized 69 kDa protein associated with some macromolecules in the cytoplasm and then was transported to peroxisomes within 15 min, and integrated into peroxisomal membranes without proteolytic processing. Proton ionophore CCCP inhibited the transport of the protein to peroxoisomal membranes.4. Polysulfonate compound suramin which have two clusters of negative charges was founded to be a potent inhibitor of the import of peroxiomal proteins. Suramin inhibited the import by interacting with peroximal membrane proteins. Suramin affected preferentially translocation step of peroxisomal proteins in the import. These results suggest that peroxisomal membrane protein(s) has important role of import of peroxisomal proteins into peroxisomes. Less