title: Membrane glycoprotein differences between normal lactating mammary tissue and the R3230 AC mammary tumor.
abstract: Membrane glycoproteins have been studied in the normal lactating mammary gland and R3230 AC mammary tumor of the rat. Plasma membrane-enriched fractions were obtained from these tissues by discontinuous sucrose gradient centrifugation of a microsomal preparation from the tissue homogenates. The lightest membrane fractions (F-1 and F-2) have the greatest enrichment of plasma membrane markers, with a 14- to 20-fold purification of 5'-nucleotidase and Na+-K+ -adenosine triphosphatase over the homogenate values in both tumor and normal tissues for F-1. Electron microscopy shows smooth membrane vesicles for these fractions. Polypeptide analysis by acrylamide gel electrophoresis shows essentially the same patterns for F-1 and F-2 and only relatively minor differences between membrane components of tumor and normal tissues. Glycoprotein analysis of the polyacrylamide gels by periodate-Schiff staining indicates more dramatic differences. Membrane Fraction F-1 from normal tissue contains two major glycoproteins, GP-II and GP-III, while Fractions F-2 and F-3 contain an additional glycoprotein, GP-I, with a higher apparent molecular weight. In the tumor, the component corresponding to GP-III is decreased or absent and a new component GP-IV is seen at a lower apparent molecular weight.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D002458:Cell Fractionation / Q000379:methods; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006023:Glycoproteins / Q000378:metabolism*; D007774:Lactation; D008321:Mammary Glands, Animal / Q000378:metabolism*; D008325:Mammary Neoplasms, Experimental / Q000378:metabolism*; D009368:Neoplasm Transplantation; D009708:Nucleotidases / Q000378:metabolism; D011247:Pregnancy; D051381:Rats
chemical_list: D006023:Glycoproteins; D009708:Nucleotidases; D000251:Adenosine Triphosphatases