Open AccessExpression of size-selected mRNA encoding the intestinal Na/glucose cotransporter in Xenopus laevis oocytes.
Author(s) -
Matthias A. Hediger,
Tyson S. Ikeda,
Michael J. Coady,
Cameron B. Gundersen,
Ernest M. Wright
Publication year - 1987
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.84.9.2634
Subject(s) - messenger rna , xenopus , microbiology and biotechnology , cotransporter , glucose transporter , biology , phlorizin , gene expression , oocyte , chemistry , biochemistry , gene , endocrinology , embryo , insulin , organic chemistry , sodium
The expression of the rabbit intestinal brushborder Na/glucose cotransporter has been studied in Xenopus oocytes. Poly(A)+ RNA isolated from the intestinal mucosa was injected into oocytes, and the expression of the transporter in the oocyte plasma membrane was assayed by measuring the Na-dependent phlorizin-sensitive uptake of methyl alpha-D-[14C]glucopyranoside (MeGlc). Expression of the glucose carrier was detected 3-7 days after mRNA injection, and the rate of glucose transport was proportional to the amount of mRNA injected. mRNA (50 ng) increased the maximum velocity (Vmax) of MeGlc uptake by as much as 10-fold over background. The total mRNA was fractionated by preparative agarose gel electrophoresis and each fraction was assayed for its ability to induce transport activity. The mRNA encoding the Na/glucose cotransporter was found in a single fraction of approximately 2.3 kilobases (kb), which contained 3% of the total mRNA. A similar mRNA fraction (2.0-2.6 kb) isolated from colon did not induce expression of this transporter. In vitro translation of the fractionated intestinal mRNA showed enhanced synthesis of two protein bands at 57 and 63 kDa. The mRNA encoding the cotransporter is smaller (2.3 kb) than that (2.6-2.9 kb) encoding the 55-kDa facilitated glucose carrier in human hepatoma cells and rat brain.