Identification of a novel alternatively spliced variant endothelin converting enzyme-1 lacking a transmembrane domain.
Endothelin-converting enzyme (ECE)-1 cleaves big endothelins, as well as bradykinin and beta-amyloid peptide. Several isoforms of ECE-1 (ECE-1a, 1b, 1c, and 1d) have been identified to date, they differ only in their amino terminus and share the catalytic domain located in the C-terminal end. In addition to full-length ECE-1 forms, we identified novel, alternatively spliced messenger RNAs (mRNAs) of ECE-1b, 1c, and 1d. These splice variants (SVs) lack exon 3', which codes for the transmembrane (TM) region and is present in full-length forms. SV mRNAs were highly expressed in endothelial cells (EC) derived from macrovascular and microvascular beds. Analyses of ECE-1d and its SV forms in stably transfected human embryonic kidney (HEK)-293 cells revealed that both proteins were recognized by antibodies to C-terminal ECE-1, but an antibody to the N-terminal only bound ECE-1d. The novel protein, designated ECE-1sv, has an apparent molecular weight of 75 kDa. ECE-1sv lacks the TM sequence (or signal peptide) and, therefore, is expected to remain cytosolic. Presence of ECE-1sv in different cellular compartments than the full-length forms of the ECE-1 may suggest a distinct physiologic role for these proteins.
Klipper
Eyal
E
Department of Animal Sciences, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
Levy
Nitzan
N
Gilboa
Tamar
T
Muller
Laurent
L
Meidan
Rina
R
D017398:Alternative Splicing; D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000737:chemistry* / Q000235:genetics*; D002417:Cattle; D002460:Cell Line; D002478:Cells, Cultured; D003338:Corpus Luteum / Q000098:blood supply; D000072396:Endothelin-Converting Enzymes; D004730:Endothelium, Vascular / Q000166:cytology*; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics; D008666:Metalloendopeptidases / Q000737:chemistry* / Q000235:genetics*; D008970:Molecular Weight; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000032:analysis; D014471:Umbilical Veins / Q000166:cytology
D007527:Isoenzymes; D012333:RNA, Messenger; D016282:Aspartic Acid Endopeptidases; D008666:Metalloendopeptidases; C000606923:ECE1 protein, human; D000072396:Endothelin-Converting Enzymes