Human hepatoma (HepG2) cells secrete a single 65 K dalton triglyceride lipase immunologically identical to postheparin plasma hepatic lipase.
A triacylglycerol lipase was isolated from the culture medium of HepG2 human hepatoma cells and its properties were compared to hepatic triglyceride lipase (H-TGL) from human postheparin plasma. The HepG2 cell enzyme bound to heparin-Sepharose, was eluted with 1 M NaCl and was not inhibited by 1 M salt. Western-blotting of the fractions from the heparin-Sepharose column with a monoclonal antibody prepared against postheparin plasma H-TGL and which binds to an epitope in the carboxyl-terminus of H-TGL gave a single immunoreactive protein band of 65 kDa. This finding of immunochemical identity was confirmed with polyclonal antibodies prepared against synthetic peptides of H-TGL corresponding to amino acid residues 82-94 near the amino-terminus and residues 468-477, the carboxyl-terminus of the enzyme. We conclude that HepG2 cells secrete a single triacylglycerol lipase with molecular weight properties and immunological characteristics identical to post-heparin plasma H-TGL.
Busch
S J
SJ
Merrell Dow Research Institute, Cincinnati, OH 45215.
Krstenansky
J L
JL
Owen
T J
TJ
Jackson
R L
RL
D000911:Antibodies, Monoclonal / Q000276:immunology; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000201:enzymology*; D000939:Epitopes / Q000032:analysis; D006801:Humans; D015151:Immunoblotting; D008049:Lipase / Q000096:biosynthesis* / Q000276:immunology; D008099:Liver / Q000201:enzymology*; D008113:Liver Neoplasms / Q000201:enzymology*; D008970:Molecular Weight; D011233:Precipitin Tests; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D000939:Epitopes; D008049:Lipase