Molecular cloning, primary structure, and expression of the human platelet/erythroleukemia cell 12-lipoxygenase
- Vanderbilt Univ., Nashville, TN (USA)
The major pathway of arachidonic acid metabolism in human platelets proceeds via a 12-lipoxygenase enzyme; however, the biological role of the product of this reaction, 12-hydro(pero)xyeicosatetraenoic acid (12-H(P)ETE), is unknown. Using a combination of the polymerase chain reaction and conventional screening procedures, the authors have isolated cDNA clones encoding the human platelet/human erythroleukemia (HEL) cell 12-lipoxygenase. From the deduced primary structure, human platelet/HEL 12-lipoxygenase would encode a M{sub r} 75,000 protein consisting of 663 amino acids. The cDNA encoding the full-length protein (pCDNA-12lx) under the control of the cytomegalovirus promoter was expressed in simian COS-M6 cells. Intact cells and lysed-cell supernatants were able to synthesize 12-H(P)ETE from arachidonic acid, whereas no 12-H(P)ETE synthesis was detected in mock-transfected cells. A single 2.4-kilobase mRNA was detected in erythroleukemia cells but not in several other tissues and cell lines evaluated by Northern blot analysis. Comparison of the human platelet/HEL 12-lipoxygenase sequence with that of porcine leukocyte 12-lipoxygenase and human reticulocyte 15-lipoxygenase revealed 65% amino acid identity to both enzymes. By contrast, the leukocyte 12-lipoxygenase is 86% identical to human reticulocyte 15-lipoxygenase. Sequence data and previously demonstrated immunochemical and biochemical evidence support the existence of distinct 12-lipoxygenase isoforms. The availability of cDNA probes for human platelet/HEL cell 12-lipoxygenase should facilitate elucidation of the biological role of this pathway.
- OSTI ID:
- 6214246
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America; (USA), Vol. 87:15; ISSN 0027-8424
- Country of Publication:
- United States
- Language:
- English
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550201* - Biochemistry- Tracer Techniques