Mammalian Sugar Transporters:Their Localization and Link to Cellular Functions.

Abstract

Sugar transporters are integral membrane proteins that transport sugars across cellular membranes. Recent advances in molecular biology have revealed two major families of them: the Na+-dependent glucose transporter (SGLT) family, and the facilitated-diffusion glucose transporter (GLUT) family. At least three isoforms of SGLT and six of GLUT have been identified so far. Expression of specific isoforms depends on the type of cell, tissue, or organ, and the physiological and pathological conditions. Their precise localization at the specific domain (s) of the plasma membrane or in the intracellular organelles is closely related to their cellular functions. In this review, their localization and link to specific cellular functions are addressed in the following cases: active transepithelial transport of glucose; glucose transport in blood-tissue barriers; possible role of glucose transporter and the gap junction in the transepithelial transport of glucose; the contribution of glucose transporters in the regulation of blood glucose level; and localization of glucose transporters at specific plasma membrane domains.

Hyperglycaemia-induced subcellular redistribution of GLUT1 glucose transporters in cultured human term placental trophoblast cells

“…Differential targeting information could reside in particular in the amino acid sequence of the four unique hydrophilic domains which display the highest degree of sequence heterogeneity among the GLUT family [21]. Moreover, specific post-translational modification of the molecules or interaction of the transporters with cytoskeletal elements could account for the distinct subcellular localisation of various glucose carriers [50]. The second difference is in the direction of hyperglycaemia-induced GLUT1 subcellular redistribution in placental trophoblast that is opposite to the insulin-induced GLUT1 and GLUT4 trafficking towards the plasma membrane described in other cells.…”

Immunohistochemical Localization of Glucose Transporters (GLUT1 and GLUT3) in the Rat Hypothalamus

“…It has been demonstrated that glucose transport across the plasma membrane is mediated by carrier systems (11). In mammalian cells, there are two known classes of glucose carriers: the Na+-glucose cotransporter and the facilitative glucose transporter (1,21 …”

Nutritional supply to the cauda equina in lumbar adhesive arachnoiditis in rats

“…Glucose is a water-soluble substance that does not easily pass through the lipid bilayer of cell membranes. However, a family of glucose transporting proteins (GLUT) allows the facilitative diffusion of D-glucose across cell membranes in a manner that is stereospecific, saturable, nonconcentrative, and not requiring energy or sodium [30]. The brain capillary endothelium is rich in GLUT 1, as it has tight intercellular junctions, constituting the blood brain barrier [3,9,10,30].…”

“…However, a family of glucose transporting proteins (GLUT) allows the facilitative diffusion of D-glucose across cell membranes in a manner that is stereospecific, saturable, nonconcentrative, and not requiring energy or sodium [30]. The brain capillary endothelium is rich in GLUT 1, as it has tight intercellular junctions, constituting the blood brain barrier [3,9,10,30]. Kumagai et al reported that the expression of GLUT 1 mRNA and protein is increased at the blood brain barrier in chronic hypoglycemia in rats [14].…”