A Human Homolog of Angiotensin-converting Enzyme
CLONING AND FUNCTIONAL EXPRESSION AS A CAPTOPRIL-INSENSITIVE CARBOXYPEPTIDASE*
- Sarah R. Tipnis‡§,
- Nigel M. Hooper‡,
- Ralph Hyde‡,
- Eric Karran¶‖,
- Gary Christie¶ and
- Anthony J. Turner‡
- From the ‡Proteolysis Research Group, School of Biochemistry and Molecular Biology, University of Leeds, Leeds LS2 9JT and ¶Neuroscience Research, SmithKline Beecham Pharmaceuticals, Harlow, Essex CM19 5AW, United Kingdom
Abstract
A novel human zinc metalloprotease that has considerable homology to human angiotensin-converting enzyme (ACE) (40% identity and 61% similarity) has been identified. This metalloprotease (angiotensin-converting enzyme homolog (ACEH)) contains a single HEXXH zinc-binding domain and conserves other critical residues typical of the ACE family. The predicted protein sequence consists of 805 amino acids, including a potential 17-amino acid N-terminal signal peptide sequence and a putative C-terminal membrane anchor. Expression in Chinese hamster ovary cells of a soluble, truncated form of ACEH, lacking the transmembrane and cytosolic domains, produces a glycoprotein of 120 kDa, which is able to cleave angiotensin I and angiotensin II but not bradykinin or Hip-His-Leu. In the hydrolysis of the angiotensins, ACEH functions exclusively as a carboxypeptidase. ACEH activity is inhibited by EDTA but not by classical ACE inhibitors such as captopril, lisinopril, or enalaprilat. Identification of the genomic sequence of ACEH has shown that the ACEH gene contains 18 exons, of which several have considerable size similarity with the first 17 exons of human ACE. The gene maps to chromosomal location Xp22. Northern blotting analysis has shown that the ACEH mRNA transcript is ∼3.4 kilobase pairs and is most highly expressed in testis, kidney, and heart. This is the first report of a mammalian homolog of ACE and has implications for our understanding of cardiovascular and renal function.
Footnotes
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↵* This work was supported by British Heart Foundation Grant PG/97192 and by UK Medical Research Council Grant G9824728.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) .
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↵§ To whom correspondence should be addressed: School of Biochemistry and Molecular Biology, University of Leeds, Leeds LS2 9JT, UK. Tel.: 44 113 233 3160; Fax: 44 113 242 3187; E-mail: s.r.tipnis@leeds.ac.uk.
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↵‖ Present address: Pfizer Central Research, Sandwich, Kent CT13 9NJ, UK.
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Published, JBC Papers in Press, August 2, 2000, DOI 10.1074/jbc.M002615200
- Abbreviations:
- ACE
-
angiotensin-converting enzyme
- ACEH
-
angiotensin-converting enzyme homolog
- AnCE
-
D. melanogaster angiotensin-converting enzyme
- ACEr
-
D. melanogaster angiotensin-converting enzyme-related
- Hip
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hippuryl
- CHO
-
Chinese hamster ovary
- HPLC
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high performance liquid chromatography
- RACE
-
rapid amplification of cDNA ends
- PCR
-
polymerase chain reaction
- PNGase F
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peptideN-glycosidase F
- PAGE
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polyacrylamide gel electrophoresis
- kb
-
kilobase pair
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- Received March 28, 2000.
- Revision received July 17, 2000.
- The American Society for Biochemistry and Molecular Biology, Inc.
