Pig intestinal microvillus aminopeptidase (EC 220.127.116.11) was reincorporated into lipid membranes by using either beta-octyl glucoside or sodium deoxycholate. The results showed that for this enzyme the deoxycholate-dialysis method was the preferable one. By using this method, microvillus aminopeptidase was inserted almost quantitatively into either phosphatidylcholine vesicles or microvillus-lipid vesicles. By proteolytic treatment of the vesicles, by probing the aminopeptidase with an inhibitory antibody and by monitoring the positioning of the anchor with the aid of [125I]iodonaphthyl azide, it was demonstrated that the catalytically active part was located outside the liposomes and the anchoring peptide(2) was associated with the membrane. Electron-microscopic observation on this model system demonstrated a dimeric symmetrical structure of aminopeptidase (dimensions about 13.5 nm X 5.5 nm) separated by a 5 nm gap from the membrane. This distance corresponds to a molecular weight of 2000-5000 for this junctional segment of the anchor connecting the intramembrane part of the anchor with the catalytically active main part of the aminopeptidase.
Reconstitution of purified amphiphilic pig intestinal microvillus aminopeptidase. Mode of membrane insertion and morphology
- Views Icon Views
- Share Icon Share
M M Hussain, J Tranum-Jensen, O Norén, H Sjöström, K Christiansen; Reconstitution of purified amphiphilic pig intestinal microvillus aminopeptidase. Mode of membrane insertion and morphology. Biochem J 1 October 1981; 199 (1): 179–186. doi: https://doi.org/10.1042/bj1990179
Download citation file: