Localization of renin (EC 3.4.23) and converting enzyme (EC 3.4.15.1) in nerve endings of rat brain.
Synaptosomes and lysosomes of rat brain were separated by differential centrifugation and a two-step gradient centrifugation with colloidal silica-gel (Percoll). The organelles were identified by the measurement of established marker-enzymes and by electronmicroscopy. Renin activity, measured by radioimmunoassay for angiotensin I (ANG I), was localized in the synaptosomes and cathepsin D-activity was found in the lysosomal fraction. Converting-enzyme activity was present in the renin-containing synaptosomes. Part of the brain renin activity could be activated by pre-incubation with trypsin. Affinity chromatography of an organelle-enriched brain fraction was carried out using a caseinyl-sepharose column and resulted in the separation of renin from cathepsin D activity; the renin peak was inhibited by antibodies raised against rat kidney renin. We conclude, that the formation of ANG I and its activation to angiotensin II (ANG II) by converting enzyme is possible in synaptosomes. This adds further evidence to an intraneuronal synthesis of ANG I and ANG II in the brain and is in support of previous results demonstrating an intraneuronal localization of the components of the brain renin-angiotensin system.
Paul
M
M
Printz
M P
MP
Harms
E
E
Unger
T
T
Lang
R E
RE
Ganten
D
D
D000818:Animals; D001921:Brain / Q000201:enzymology*; D002402:Cathepsin D / Q000378:metabolism; D008247:Lysosomes / Q000201:enzymology; D008297:Male; D008854:Microscopy, Electron; D009411:Nerve Endings / Q000201:enzymology; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012083:Renin / Q000378:metabolism*; D013574:Synaptosomes / Q000201:enzymology
D007703:Peptidyl-Dipeptidase A; D012083:Renin; D002402:Cathepsin D