Subcellular distribution of small GTP-binding proteins in the intestinal cell line Caco-2. 1995

J Stein, and R Gerhard, and S Zeuzem, and W F Caspary
2nd Department Medicine, Johann-Wolfgang-Goethe-University, Frankfurt, Germany.

The present study describes the subcellular distribution of low molecular weight GTP-binding proteins in the human carcinoma cell line Caco-2. Highly enriched subcellular fractions of basolateral and brush border membranes were prepared by differential density centrifugation and divalent cation precipitation. Small molecular weight GTP-binding proteins were identified after SDS-PAGE transfer to nitrocellulose using [alpha 32P]-labelled GTP. Smg-proteins with molecular masses of 28, 27, 25 and 24 kDa were detectable in all fractions. Homogenate and brush border membrane fraction showed specific binding of [alpha 32P] GTP to proteins of a molecular mass of 21 kDa, while in the membrane fractions (apical, basolateral) a high enrichment of 24 kDa smg-proteins was detectable. Western blot analysis identified one of the 21 kDa proteins of the brush border membrane as rhoA. The homogenate of 4, 8, 11 and 14 days old Caco-2 cells showed different [alpha 32P]-GTP binding to 21, 27 and 28 kDa proteins. In conclusion, this study is the first showing the presence and asymmetrical distribution of smg-proteins among the various membrane components in the human carcinoma cell line Caco-2.

UI MeSH Term Description Entries
D007422 Intestines The section of the alimentary canal from the STOMACH to the ANAL CANAL. It includes the LARGE INTESTINE and SMALL INTESTINE. Intestine
D008970 Molecular Weight The sum of the weight of all the atoms in a molecule. Molecular Weights,Weight, Molecular,Weights, Molecular
D002454 Cell Differentiation Progressive restriction of the developmental potential and increasing specialization of function that leads to the formation of specialized cells, tissues, and organs. Differentiation, Cell,Cell Differentiations,Differentiations, Cell
D002462 Cell Membrane The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells. Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D018938 Caco-2 Cells Human colonic ADENOCARCINOMA cells that are able to express differentiation features characteristic of mature intestinal cells, such as ENTEROCYTES. These cells are valuable in vitro tools for studies related to intestinal cell function and differentiation. Caco 2 Cells,Caco-2 Cell,Cell, Caco-2,Cells, Caco-2
D019204 GTP-Binding Proteins Regulatory proteins that act as molecular switches. They control a wide range of biological processes including: receptor signaling, intracellular signal transduction pathways, and protein synthesis. Their activity is regulated by factors that control their ability to bind to and hydrolyze GTP to GDP. EC 3.6.1.-. G-Proteins,GTP-Regulatory Proteins,Guanine Nucleotide Regulatory Proteins,G-Protein,GTP-Binding Protein,GTP-Regulatory Protein,Guanine Nucleotide Coupling Protein,G Protein,G Proteins,GTP Binding Protein,GTP Binding Proteins,GTP Regulatory Protein,GTP Regulatory Proteins,Protein, GTP-Binding,Protein, GTP-Regulatory,Proteins, GTP-Binding,Proteins, GTP-Regulatory

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