title: Membrane domains and macromolecular transport in intestinal epithelial cells.
abstract: Epithelial cell plasma membranes are organized as biochemically and functionally distinct domains and subdomains. We have explored the composition and maintenance of specific membrane regions during endocytosis and transepithelial vesicular transport in specialized cells of the intestinal epithelium. A unique membrane glycoprotein has been identified in apical endocytic subdomains and endosomal tubules of absorptive cells in suckling rat ileum. This endocytic system is involved in sorting and transepithelial transport of peptide growth factors as well as delivery of milk macromolecules to lysosomes. In M cells of follicle-associated epithelium, we have shown that membrane-bound proteins are efficiently transported to a specialized subdomain of basolateral membrane. The apical membranes of these cells bear immunoglobulin binding sites and transport monoclonal IgA antibodies to the basolateral side, where they may interact with cells of the mucosal immune system.
authors.affiliation: Department of Anatomy and Cellular Biology, Harvard Medical School, Boston, Massachusetts 02115.
authors.forename: M R
authors.initials: MR
authors.lastname: Neutra
authors.forename: J M
authors.initials: JM
authors.lastname: Wilson
authors.forename: R A
authors.initials: RA
authors.lastname: Weltzin
authors.forename: J P
authors.initials: JP
authors.lastname: Kraehenbuhl
mesh_terms: D000042:Absorption; D000818:Animals; D001692:Biological Transport; D002462:Cell Membrane / Q000276:immunology / Q000378:metabolism*; D004705:Endocytosis; D004848:Epithelium / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism; D007421:Intestine, Small / Q000166:cytology / Q000378:metabolism*; D051381:Rats
chemical_list: D006023:Glycoproteins