Editors' ChoiceCell Biology

Glucose Sensor, Not Cotransporter

STKE  07 Oct 2003:
Vol. 2003, Issue 203, pp. tw389-TW389
DOI: 10.1126/stke.2003.203.tw389

Díez-Sampedro et al. characterized the human SGLT3 (hSGLT3) member of the SLC family of sodium and glucose transporters and found that its expression was limited. Immunohistochemistry showed that the protein colocalized with nicotinic acetylcholine receptors in skeletal muscle and intestine. (The resolution was too low to determine pre- or postsynaptic location at the neuromuscular junction; however, in intestine, hSGLT3 was present in the cholinergic neurons of the submucosal myoenteric plexuses.) Expression of the protein in Xenopus oocytes did not show any increase in glucose uptake; instead, exposure of the oocytes to D-glucose or nonmetabolizable analogs produced a depolarization response that appeared to be the result of an inward Na+ current. Thus, hSGLT3 appears to be a glucose sensor that triggers cellular depolarization, without acting as a cotransporter.

A. Díez-Sampedro, B. A. Hirayama, C. Osswald, V. Gorboulev, K. Baumgarten, C. Volk, E. M. Wright, H. Koepsell, A glucose sensor hiding in a family of transporters. Proc. Natl. Acad. Sci. U.S.A. 100, 11753-11758 (2003). [Abstract] [Full Text]