Angiotensin AT4 receptor ligand interaction with cystinyl aminopeptidase and aminopeptidase N: [125I]Angiotensin IV only binds to the cystinyl aminopeptidase apo-enzyme.
Due to its high affinity for [(125)I]Angiotensin IV, cystinyl aminopeptidase (CAP) has recently been assigned as the 'angiotensin AT(4) receptor'. Since the aminopeptidase N (AP-N) activity is also susceptible to inhibition by Angiotensin IV, it might represent an additional target for this peptide. Based on [(125)I]Angiotensin IV binding and catalytic activity measurements, we compared the ligand interaction properties of recombinant human CAP and human AP-N. Both enzymes displayed distinct pharmacological profiles. Although their activity is inhibited by Angiotensin IV and LVV-hemorphin 7, both peptides are more potent CAP-inhibitors. On the other hand, substance P and l-methionine have a higher potency for AP-N. High affinity binding of [(125)I]Angiotensin IV to CAP occurs in the presence of chelators but not to AP-N in either the absence or presence of chelators. These differences were exploited to determine whether CAP and/or AP-N are present in different cell lines (CHO-K1, COS-7, HEK293, SK-N-MC and MDBK). We provide evidence that CAP predominates in these cell lines and that, comparatively, CHO-K1 cells display the highest level of this enzyme.
Demaegdt
Heidi
H
Research Group on Experimental Pharmacology, Department of Molecular and Biochemical Pharmacology, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium. hdemaegd@vub.ac.be
Lenaerts
Pieter-Jan
PJ
Swales
Julie
J
De Backer
Jean-Paul
JP
Laeremans
Hilde
H
Le
Minh Tam
MT
Kersemans
Ken
K
Vogel
Lotte K
LK
Michotte
Yvette
Y
Vanderheyden
Patrick
P
Vauquelin
Georges
G
D000804:Angiotensin II / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D001667:Binding, Competitive; D018826:CD13 Antigens / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D016466:CHO Cells; D019556:COS Cells; D002462:Cell Membrane / Q000378:metabolism; D002522:Chlorocebus aethiops; D006224:Cricetinae; D003412:Cricetulus; D010122:Cystinyl Aminopeptidase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D004285:Dogs; D004791:Enzyme Inhibitors / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007457:Iodine Radioisotopes; D007700:Kinetics; D008024:Ligands; D011485:Protein Binding; D011945:Receptors, Angiotensin / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection
C090830:AT4 receptor; D057911:Angiotensin Receptor Antagonists; D004791:Enzyme Inhibitors; D007457:Iodine Radioisotopes; D008024:Ligands; D011945:Receptors, Angiotensin; D011994:Recombinant Proteins; D000804:Angiotensin II; C012877:angiotensin II, des-Asp(1)-des-Arg(2)-Ile(5)-; D018826:CD13 Antigens; D010122:Cystinyl Aminopeptidase