Subcellular localization of monoglyceride acyltransferase, xanthine oxidation, NADP: isocitrate dehydrogenase and alkaline phosphatase in the mucosa of the guinea-pig small intestine.

Abstract

1. Rate dependent and isopycnic banding in a zonal rotor were used to analyse the subcellular sites of enzymes in homogenates of guinea-pig small intestinal mucosa. 2, The results demonstrate the following localizations: monoglyceride acyltransferase-microsomal; xanthine oxidase and dehydrogenase-soluble phase, and NADP: isocitrate dehydrogenase-soluble phase and mitochondrial. 3, Alkaline phosphatase is confined to brush borders and is absent from the basolateral plasma membrane. A variable proportion of the activity, up to 40%, is on brush borders which during homogenization break up into particles of reduced density and slow sedimentation rate.