title: Two di-leucine-based motifs account for the different subcellular localizations of the human endothelin-converting enzyme (ECE-1) isoforms.
abstract: Endothelin-converting enzyme (ECE-1) is a type II integral membrane protein which plays a key role in the biosynthetic pathway of the vasoconstricting endothelins. Three ECE-1 isoforms, differing by their N-terminal cytoplasmic tails, are generated from a single gene. When expressed in CHO cells, they display comparable enzymatic activity but whereas ECE-1a is strongly expressed at the cell surface, ECE-1b is exclusively intracellular and ECE-1c presents an intermediate distribution. In the present study these different localizations were further described at the ultrastructural level, by electron microscope immunocytochemistry. To characterize the motifs responsible for the intracellular localization of ECE-1b we constructed chimeric proteins and point mutants. Two di-leucine-based motifs, contained in the N-terminal part of ECE-1b, were thus identified. One of these motifs (LV), displayed by both ECE-1b and ECE-1c, accounts for the reduced surface expression of ECE-1c as compared to ECE-1a. Mutation of both motifs (LL and LV) induces a very strong appearance of ECE-1b at the cell surface indicating that their presence in the N-terminal extremity of ECE-1b is critical for its exclusively intracellular localization.
authors.affiliation: INSERM U460, UFR X.Bichat, France.
authors.forename: O
authors.initials: O
authors.lastname: Valdenaire
authors.forename: A
authors.initials: A
authors.lastname: Barret
authors.forename: A
authors.initials: A
authors.lastname: Schweizer
authors.forename: E
authors.initials: E
authors.lastname: Rohrbacher
authors.forename: F
authors.initials: F
authors.lastname: Mongiat
authors.forename: F
authors.initials: F
authors.lastname: Pinet
authors.forename: P
authors.initials: P
authors.lastname: Corvol
authors.forename: C
authors.initials: C
authors.lastname: Tougard
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016466:CHO Cells; D002462:Cell Membrane / Q000201:enzymology; D006224:Cricetinae; D004151:Dipeptides / Q000737:chemistry; D000072396:Endothelin-Converting Enzymes; D005455:Fluorescent Antibody Technique; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008666:Metalloendopeptidases; D016253:Microscopy, Immunoelectron; D016297:Mutagenesis, Site-Directed; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000201:enzymology
chemical_list: D004151:Dipeptides; D007527:Isoenzymes; D011993:Recombinant Fusion Proteins; C038361:leucylleucine; D016282:Aspartic Acid Endopeptidases; D008666:Metalloendopeptidases; C000606923:ECE1 protein, human; D000072396:Endothelin-Converting Enzymes