According to the article, glucose transporters' main job is to make it easier for glucose to cross a cell's plasma membrane. All phyla of living animals have these transporters since glucose is a crucial source of energy for cells. These glucose transporters, which range from GLUT1 to GLUT14, each make it easier for monosaccharides to diffuse across the cell membranes of living animals' bodies.
Unique Characteristics and Locations
Each of these transporters has a unique pattern of tissue distribution, gene regulation, and kinetic characteristics and is found in various locations throughout the body. GLUT5 is located in the lower abdomen region, in the intestines and facilitates the transportation of both glucose and fructose through diffusion. This is possible given the intestinal lumen has a high concentration of fructose. GLUT5 can also be found in the kidney region and in fat tissues.
Transport Mechanism in GLUT5
Transport in GLUT5 is controlled by both the rocker-switch-type movement of the N- and C-terminal TM bundles and by a gated-pore mechanism gating movements by TM7 and TM10 in the C-terminal TM bundle that are coupled to substrate binding and release. In GLUT5, Trp419 is the only tryptophan positioned in the substrate-binding site, and it is essential for transport. Consistent with GLUT5 transport activity, strong quenching of tryptophan fluorescence could be observed with the addition of D-fructose, but not with the addition of GLUT1 substrates like D-glucose and D-mannose.
Structural Basis of Transport in GLUT5
Symmetrical substrate binding and rigid-body movements of the N- and C-terminal TM bundles around a centrally located substrate-binding site form the structural basis of the 'rocker-switch' mechanism in GLUT5 transporter. Salt bridges stabilize the outwards conformation from the cell. A common feature observed in recent structures of GLUT transporters are inter-TM bundle salt bridges that break and form near the central cavity during transport.
