We have used the recombinant NH₂-terminal myc-tagged rabbit Na⁺-glucose transporter (SGLT1) to study the regulation of this carrier expressed in COS-7 cells. Treatment of cells with a protein kinase C (PKC) agonist, phorbol 12-myristate 13-acetate (PMA), caused a significant decrease (38.03 ± 0.05%) in methyl -D-glucopyranoside transport activity that could not be emulated by 4-phorbol 12,13-didecanoate. The decrease in sugar uptake stimulated by PMA was reversed by the PKC inhibitor bisindolylmaleimide I. The maximal rate of Na⁺-glucose cotransport activity (V_max) was decreased from 1.29 ± 0.09 to 0.85 ± 0.04 nmol · min¹ · mg protein¹ after PMA exposure. However, measurement of high-affinity Na⁺-dependent phloridzin binding revealed that there was no difference in the number of cell surface transporters after PMA treatment; maximal binding capacities were 1.54 ± 0.34 and 1.64 ± 0.21 pmol/mg protein for untreated and treated cells, respectively. The apparent sugar binding affinity (Michaelis-Menten constant) and phloridzin binding affinity (dissociation constant) were not affected by PMA. Because PKC reduced V_max without affecting the number of cell surface SGLT1 transporters, we conclude that PKC has a direct effect on the carrier, resulting in a lowering of the transporter turnover rate by a factor of two.

rabbit SGLT1; protein kinase C; regulation

This article has been cited by other articles:

				J. Garcia-Herrera, M. C. Marca, E. Brot-Laroche, N. Guillen, S. Acin, M. A. Navarro, J. Osada, and M. J. Rodriguez-Yoldi Protein kinases, TNF-{alpha}, and proteasome contribute in the inhibition of fructose intestinal transport by sepsis in vivo Am J Physiol Gastrointest Liver Physiol, January 1, 2008; 294(1): G155 - G164. [Abstract] [Full Text] [PDF]

				F. Zhou, M. Hong, and G. You Regulation of human organic anion transporter 4 by progesterone and protein kinase C in human placental BeWo cells Am J Physiol Endocrinol Metab, July 1, 2007; 293(1): E57 - E61. [Abstract] [Full Text] [PDF]

				M. Veyhl, T. Keller, V. Gorboulev, A. Vernaleken, and H. Koepsell RS1 (RSC1A1) regulates the exocytotic pathway of Na+-D-glucose cotransporter SGLT1 Am J Physiol Renal Physiol, December 1, 2006; 291(6): F1213 - F1223. [Abstract] [Full Text] [PDF]

				F. Artunc, R. Rexhepaj, H. Volkl, F. Grahammer, C. Remy, D. Sandulache, O. Nasir, C. A. Wagner, D. R. Alessi, and F. Lang Impaired intestinal and renal glucose transport in PDK-1 hypomorphic mice Am J Physiol Regulatory Integrative Comp Physiol, November 1, 2006; 291(5): R1533 - R1538. [Abstract] [Full Text] [PDF]

				Y. Kimura, J. R. Turner, D. A. Braasch, and R. K. Buddington Lumenal adenosine and AMP rapidly increase glucose transport by intact small intestine Am J Physiol Gastrointest Liver Physiol, December 1, 2005; 289(6): G1007 - G1014. [Abstract] [Full Text] [PDF]

				C. Osswald, K. Baumgarten, F. Stumpel, V. Gorboulev, M. Akimjanova, K.-P. Knobeloch, I. Horak, R. Kluge, H.-G. Joost, and H. Koepsell Mice without the Regulator Gene Rsc1A1 Exhibit Increased Na+-D-Glucose Cotransport in Small Intestine and Develop Obesity Mol. Cell. Biol., January 1, 2005; 25(1): 78 - 87. [Abstract] [Full Text] [PDF]

				W.-J. Liang, D. Johnson, L.-S. Ma, and S. M. Jarvis Regulation of the human vitamin C transporters expressed in COS-1 cells by protein kinase C Am J Physiol Cell Physiol, December 1, 2002; 283(6): C1696 - C1704. [Abstract] [Full Text] [PDF]

				A. Ikari, M. Nakano, K. Kawano, and Y. Suketa Up-regulation of Sodium-dependent Glucose Transporter by Interaction with Heat Shock Protein 70 J. Biol. Chem., August 30, 2002; 277(36): 33338 - 33343. [Abstract] [Full Text] [PDF]

				N. Halaihel, V. Lievin, F. Alvarado, and M. Vasseur Rotavirus infection impairs intestinal brush-border membrane Na+-solute cotransport activities in young rabbits Am J Physiol Gastrointest Liver Physiol, September 1, 2000; 279(3): G587 - G596. [Abstract] [Full Text] [PDF]