Pore properties of the Golgi membrane from lactating-rat mammary gland. Effects of pH and temperature and reconstitution into phospholipid vesicles

Golgi-membrane vesicle penetration was studied by osmotic lysis. Pronounced temperature dependence of mannitol and mannoheptitol penetration over 0-37 degrees C gave linear Arrhenius plots, with activation energies of 75 and 117 kJ/mol respectively. Glucose penetration was constant over pH 5-9, but was respectively faster and slower at higher and lower pH values. Solubilized, dialysed, heat-stable extracts of Golgi membrane were reconstituted into egg yolk phospholipid membranes with apparent recovery of specific permeability. Penetration is interpreted in terms of a pore, for which the Renkin equation predicts a radius of about 0.54 nm.