Glycoproteins of the brush border membrane of mouse duodenum

Qualitative and quantitative chemical analyses have been made of the carbohydrate and protein moieties of the glycoproteins in purified mouse duodenal brush border membranes. Solubilized membrane protein was electrophoresed on S.D.S.--polyacrylamide gels and glycoproteins were subsequently identified by periodate-Schiff staining. A parallel experiment showed that these glycoprotein bands also incorporated 14C counts from intraluminally-administered 14C-glucosamine. Positively-staining bands were collected from several identically run gels and subjected to digestion with pronase. The sugar and amino acid compositions of the digested glycoproteins were determined. Five of the membrane proteins appeared to be complexed with sugars, and further analyses showed that there were differences between the glycoproteins with respect to sialic acid, uronic acid, amino acids, amino sugar and monosaccharide contents.