Ingrid Monden

Learn More
The first autosomal dominant missense mutation (G272A) reported within the human GLUT1 gene and shared by three affected family members was investigated in respect to functional consequences. Substitution of glycine-91 by site-directed mutagenesis with either aspartate or alanine resulted in a significant decrease in transport activity of GLUT1 expressed in(More)
Cys-421 and Cys-429 of Glut1 were replaced by site-directed mutagenesis in order to investigate their involvement in basal glucose transport and transport inhibition. Neither of the two cysteine residues was essential for basal 2-deoxy-D-glucose uptake in Xenopus oocytes expressing the respective mutant M421 and M429. If applied from the external side, the(More)
Cysteine scanning mutagenesis in conjunction with site-directed chemical modification of sulfhydryl groups by p-chloromercuribenzenesulfonate (pCMBS) or N-ethylmaleimide (NEM) was applied to putative transmembrane segments (TM) 2 and 7 of the cysteine-less glucose transporter GLUT1. Valid for both helices, the majority of cysteine substitution mutants(More)
The tryptophan residues 388 and 412 in the glucose transporter GLUT1 were altered to leucine (L) by site-directed mutagenesis and were transiently expressed in COS-7 cells. As assessed by immunoblotting, comparable numbers of glucose transporters were present in plasma membranes from cells transfected with wild-type GLUT1, GLUT1-L388 or GLUT1-L412.(More)
Proline residues are thought to play a characteristic structural and/or dynamic role in various membrane proteins [Williams, K.A. & Deber, C.M. (1991) Biochemistry 30, 8919-8923]. By use of site-directed mutagenesis and functional expression of mutant glucose transporters in Xenopus oocytes, we investigated the effects of single proline substitutions in the(More)
In adipose and muscle cells, the glucose transporter isoform GLUT4 is mainly located in an intracellular, vesicular compartment from which it is translocated to the plasma membrane in response to insulin. In order to test the hypothesis that this preferential targeting of a glucose transporter to an intracellular storage site is conferred only by its(More)
To investigate local secondary structure of GLUT1, site-directed and cysteine-scanning mutagenesis were employed to probe p-chloromercuribenzenesulfonate sensitivity of flanking regions at the boundary of external loops (ELs) and transmembrane segments (TMs) and to check the compatibility of two alternative membrane topology models with the experimental(More)
The functional consequences of an in vivo heterozygous insertion mutation in the human facilitated glucose transporter isoform 1 (GLUT1) gene were investigated. The resulting frameshift in exon 10 changed the primary structure of the C-terminus from 42 in native GLUT1 to 61 amino acid residues in the mutant. Kinetic studies on a patient's erythrocytes were(More)
Two triple cysteine mutants containing Cys-less N- or C-terminal halves and the Cys-less GLUT1 were generated by site-directed mutagenesis. Following expression in Xenopus oocytes, the intrinsic transport activities of the multiple cysteine mutants were slightly decreased when either the cysteine residues of the C-terminal half or all six residues were(More)
To evaluate the role of the small rab GTP-binding proteins in glucose transporter trafficking, we have heterologously co-expressed rab4 or rab5 and GLUT4 or GLUT1 glucose transporters in Xenopus oocytes. Co-injection of rab4 and GLUT4 cRNAs resulted in a dose-dependent decrease in glucose transport; this effect was specific for rab4, since co-injection of(More)