A modified procedure for the rapid preparation of efficiently transporting vesicles from small intestinal brush border membranes. Their use in investigating some properties of d-glucose and choline transport systems

Phosphatidylcholine exchange between brush border membrane vesicles and sonicated liposomes

“…It is now well documented that lipid exchange proteins do neither exert lytic effects on membranes nor do they affect the permeability properties of membranes [l l-131. Brush border membrane vesicles prepared by this procedure [3] or by a related one [4] have been shown to be impermeable to molecules as large as glutathione [14] and metoxyinulin [4,15] and, furthermore, that with the kind of membrane preparation used in this work >9.5% of the membrane vesicles are sealed and right side out [14]. However, the membrane integrity of brush border vesicles in the presence of liposomes was checked by measuring the ability of the brush border vesicles to take up D-glucose [4].…”

“…The membrane studied in this work is, however, the first epithelial plasma membrane investigated in this respect. Rapid phospholipid flip-flop in brush border plasma membrane could be related to the process of fat absorption The Dglucose uptake of brush border membrane vesicles was measured under equilibrium conditions [4]. Vesicles in buffer (1 mg protein/ml) were equilibrated with D- [l-3H]glucose at 20°C for 80 min.…”

“…The buffer used throughout this work was 10 mM Hepes/KOH (PH 7 S) containing 0.3 M D-mannitol and 1 mM EDTA. To test whether or not these membrane vesicles are closed and stable in the presence of sonicated egg phosphatidylcholine liposomes, D-glucose uptake was measured according to [4] in the presence of liposomes. Lipids were extracted from brush border membrane vesicles according to [5].…”

Chemical cross‐linking leads to two high molecular mass aggregates of rat α1β1 integrin differing in their conformation but not in their composition

“…Formation of the 2401290 kDa aggregates was completely prevented if the samples were denatured by SDS/boiling or treated with DTT prior to cross-linking. However, the success of cross-linking did not depend on the presence of divalent cations like Ca 2÷ (data not shown), which have been shown to be important for the formation of an active ligand binding site of integrins [19][20][21].…”

Role of intestinal brush border membrane aminopeptidase N in dipeptide transport

“…Brush border membrane vesicles of porcine small intestine were obtained from mucosa as in [13]. [14].…”