Sequence and Structure of a Human Glucose Transporter

Abstract

The amino acid sequence of the glucose transport protein from human HepG2 hepatoma cells was deduced from analysis of a complementary DNA clone. Structural analysis of the purified human erythrocyte glucose transporter by fast atom bombardment mapping and gas phase Edman degradation confirmed the identity of the clone and demonstrated that the HepG2 and erythrocyte transporters are highly homologous and may be identical. The protein lacks a cleavable amino-terminal signal sequence. Analysis of the primary structure suggests the presence of 12 membrane-spanning domains. Several of these may form amphipathic alpha helices and contain abundant hydroxyl and amide side chains that could participate in glucose binding or line a transmembrane pore through which the sugar moves. The amino terminus, carboxyl terminus, and a highly hydrophilic domain in the center of the protein are all predicted to lie on the cytoplasmic face. Messenger RNA species homologous to HepG2 glucose transporter messenger RNA were detected in K562 leukemic cells, HT29 colon adenocarcinoma cells, and human kidney tissue.

Expression of the glucose transporter GLUT4 in the muscular dystrophic mdx mouse

“…Two transporters are found in skeletal muscle: (a) the major transporter, GLUT4, which occurs exclusively in muscle and adipose tissue, and which is thought to be responsible for insulin-stimulated glucose transport [17][18][19][20][21], and (b) the ubiquitous GLUTI glucose transporter, which is the major brain transporter and is also present in very small amounts in skeletal muscle [22,23]. The aim of the present study was to investigate GLUT4 expression at both the protein and the mRNA levels in the mdx mouse.…”

Rapid purification of a functionally active plant sucrose carrier from transgenic yeast using a bacterial biotin acceptor domain

“…Information on the secondary structure of th~:se proteins has been obtained primarily from studies of the £,cherichia eoli lactose permease and of different mammalian m mosaccharide uniporters. A topological model with 12 putatix e transmembrane helices was first suggested for a human ghLcose uniporter [2] and later confirmed by others [3][4][5].…”

Contribution of Known and Unknown Susceptibility Genes to Early-Onset Diabetes in Scandinavia

“…Only two obvious candidate genes are found in the 22q11-13 region: the intestinal sodium/glucose co-transporter (SLC5A1; MIM*182380), which is responsible for "active" transepithelial glucose absorption (51), and the cytochrome c oxidase 7b (COX7b; MIM*603792), which is a subunit of the terminal component of the respiratory chain complex (52). The respiratory chain complex has been implicated in regulation of insulin secretion in a mouse model for mitochondrial diabetes (53).…”