SLC5A9/SGLT4, a new Na+-dependent glucose transporter, is an essential transporter for mannose, 1,5-anhydro-D-glucitol, and fructose

Identification of a novel sodium-dependent fructose transport activity in the hepatopancreas of the Atlantic lobsterHomarus americanus

“…Fructose transport by BLMV was also sodium dependent. This observation is consistent with a fructose, sodium-dependent transporter in BLMV in contrast to the mammalian fructose transport paradigm that involves GLUT5 and SGLT4 present in the BBMV of mammalian intestinal and renal epithelia (Mahraoui et al, 1992;Tazawa et al, 2005). It should be noted that sodium-dependent fructose transport activity was observed in both BBMV and BLMV from the whole hepatopancreas and not the BBMV and BLMV from isolated E-, R-, F-and B-cells.…”

“…EX471402) was submitted to BLAST (Altschul et al, 1997) analysis using human SGLT4 (Tazawa et al, 2005), rabbit SGLT1 (Hediger et al, 1987), mouse (Accession no. AAF17249) SGLT1, Pacific oyster SGLT (Huvet et al, 2004), rat GLUT2 (Fisher et al, 2008) and rat GLUT5 (Rand et al, 1993) protein sequences for identification of expressed lobster sugar transport orthologues.…”

Inhibitor Binding in the Human Renal Low- and High-Affinity Na+/Glucose Cotransporters

“…In addition, the newer compounds are more selective for SGLT2 than SGLT1, thus minimizing potential side effects associated with the broad tissue distribution of SGLT1. Besides intestine and kidney, SGLT1 is found in other organs and tissues, including blood-brain barrier and heart (Zhou et al, 2003;Elfeber et al, 2004;Tazawa et al, 2005). In diabetic animal models, inhibition of SGLT2 produces glucosuria, followed by a normalization of blood glucose levels and a consequent improve-ment in insulin resistance and renal damage (Asano et al, 2004;Katsuno et al, 2007).…”

Transepitheliald-glucose andd-fructose transport across the American lobster,Homarus americanus, intestine

“…In contrast, epithelial transport of D-fructose by both invertebrate epithelial cells significantly departed from the mammalian paradigm by displaying sodium-dependent transport at both cell poles that was unaffected by a 10-fold excess concentration of D-glucose. As discussed in Sterling and Ahearn's paper (Sterling and Ahearn, 2011), BLAST sequence alignments of horseshoe crab cDNA with mouse SGLT4 protein sequence and lobster sequence alignments with human SGLT4 protein sequence (Sterling et al, 2009) suggested the high probability of orthologs of this sodium-dependent mammalian D-fructose transporter (Tazawa et al, 2005) being present in both invertebrates. Sodium-dependent D-glucose and D-fructose transport in the same digestive tract epithelium is a significant departure from the sugar transport properties characterized in many vertebrate and invertebrate species, suggesting a potentially more diverse arrangement of sugar transport proteins at sites of nutrient absorption than strictly defined by the mammalian paradigm.…”