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Purification and characterization of a soluble form of lysosome‐associated membrane glycoprotein‐2 (lamp‐2) from rat liver lysosomal contents
Author(s) -
Akasaki Kenji,
Tsuji Hiroshi
Publication year - 1998
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1080/15216549800203702
Subject(s) - chemistry , isoelectric point , glycoprotein , membrane , lysosome , sialic acid , biochemistry , membrane glycoproteins , isoelectric focusing , gel electrophoresis , polyacrylamide gel electrophoresis , size exclusion chromatography , electrophoresis , chromatography , microbiology and biotechnology , biology , enzyme
Lysosomal membrane of rat liver contains a highly glycosylated protein referred to as lamp‐2. Lamp‐2 occurs to a significant extent in a soluble fraction of rat liver lysosomes. The soluble form of lamp‐2 (SF‐lamp‐2) was purified to electrophoretic homogeneity. An apparent molecular weight (Mr) of SF‐lamp‐2 on sodium dodecy sulfate‐polyacrylamide gel electrophoresis was determined to be 91,000 which is 5,000 less than that of the membranous form of lamp‐2 (MF‐lamp‐2). SF‐ and MF‐lamp‐2 were very similar to each other in terms of sialic acid content, NH2‐terminal amino acid sequence and isoelectric point. Gel filtration data indicated that native SF‐lamp‐2 has an Mr=360,000. Taken together, SF‐lamp‐2 forms a tetrameric structure consisiting of a homogenous polypeptide lacking a membrane‐spanning domain and a cytoplasmic tail near the COOH‐terminus.