| Abstract: |
Protein ectodomain shedding is a specialized type of regulated proteolysis that releases the extracellular domain of transmembrane proteins. The metalloprotease disintegrin tumor necrosis factor-α-converting enzyme (TACE) has been convincingly shown to play a central role in ectodomain shedding, but despite its broad interest, very little is known about the mechanisms that regulate its activity. An analysis of the biosynthesis of TACE in mutant cell lines that have a gross defect in ectodomain shedding (M1 and M2) shows a defective removal of the prodomain that keeps TACE in an inactive form. Using LoVo, a cell line that lacks of active furin, and α1-Antitrypsin Portland, a protein inhibitor of proprotein convertases, we show that TACE is normally processed by furin and other proprotein convertases. The defect in MI and M2 cells is due to a blockade of the exit of TACE from the endoplasmic reticulum. The processing of other zinc-dependent metalloproteases, previously suggested to participate in activated ectodomain shedding is normal in the mutant cells, indicating that the component mutated is highly specific for TACE. In summary, the characterization of shedding-defective somatic cell mutants unveils the existence of a specific mechanism that directs the proteolytic activation of TACE through the control of its exit from the ER. |
| Keywords: |
controlled study; unclassified drug; gene mutation; human cell; mutation; nonhuman; protein domain; animal cell; animals; somatic cell; microscopy, confocal; protein degradation; cell line; enzyme activation; tumor cells, cultured; hela cells; transfection; animalia; blotting, western; endoplasmic reticulum; biosynthesis; protein processing; molecular sequence data; tumor necrosis factor-alpha; reverse transcriptase polymerase chain reaction; tumors; nucleotide sequence; protein transport; cellular distribution; microscopy, fluorescence; protein structure, tertiary; zinc; glycoproteins; enzymes; cell mutant; enzyme synthesis; metalloproteinase; transforming growth factor alpha; adam proteins; alpha 1 antitrypsin; dna, complementary; biotinylation; furin; cho cells; cricetinae; isoenzyme; tumor necrosis factor alpha converting enzyme; metalloendopeptidases; precipitin tests; alpha 1-antitrypsin; humans; human; priority journal; article; cell mutants; proprotein convertase
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