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KMID : 1161520000040020165
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Animal Cells and Systems
2000 Volume.4 No. 2 p.165 ~ p.171
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Characterization of ubiquitinated lysosomal membrane proteins in acanthamoeba castellanii
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Oh Se-Kyung
Ahn Tae-In
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Abstract
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Ubiquitinated proteins in lysosomes were characterized by using two monoclonal antibodies (mAbs): LYS8?1, a mAb to lysosomal proteins, and NYA124, a mAb to ubiquitin. LYS8?1 stained lysosome?like vesicles in immunofluore?scence microscopy of Amoeba proteus and Acanthamoeba castellanii. In immunoblotting, LYS8?1 ‘s antigens (LYS proteins) were detected as 68?kDa and 77?kDa proteins in A. proteus, and as 30?kDa and 39?kDa proteins in A. castellanii. In immunoprecipitation of A. castellanii, at least four distinct LYS proteins, LYS35p, LYS39p, LYS42p, and LYS46p, were detected and accumulated upon inhibition of lysosome functions but not upon that of 26S proteasome functions. They were all found to be ubiquitinated, and were recovered in the lysosome fractions in subcellular fractionation experiments. In chemical fractionation analyses, LYS35p and LYS39p were demonstrated to be peripherally associated with lysosome membrane, while LYS42p and LYS46p tightly bound to the membrane. These results suggest that the LYS proteins become associated to lysosomal membrane upon ubiquitination.
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KEYWORD
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Ubiquitin, Lysosomes, Amoeba proteus, Acanthamoeba castellanii
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