TY - JOUR
T1 - Reanalysis of structure/function correlations in the region of transmembrane segments 4 and 5 of the rabbit sodium/glucose cotransporter
AU - Liu, Tiemin
AU - Speight, Pam
AU - Silverman, Mel
N1 - Funding Information:
This work was supported by Canadian Institutes of Health Research Grant MOP-15267.
PY - 2009/1/2
Y1 - 2009/1/2
N2 - The predicted topology of the mammalian high-affinity sodium/glucose cotransporter (SGLT1), in the region surrounding transmembrane segments 4 and 5, disagrees with the recent published crystal structure of bacterial SGLT from Vibrio parahaemolyticus (vSGLT). To investigate this issue further, 38 residues from I143 to A180 in the N-terminal half of rabbit SGLT1 were each replaced with cysteine and then expressed in COS-7 cells or Xenopus laevis oocytes. The membrane orientations of the substituted cysteines were determined by treatment with the thiol-specific reagent N-Biotinoylaminoethyl methanethiosulfonate (biotin-MTSEA), combined with the membrane impermeant thiol-specific reagent sodium (2-sulfonatoethyl) methanethiosulfonate (MTSES). The present results combined with previous structure/function studies of SGLT1, suggest that transmembrane domain (TM) 4 of mammalian SGLT1 extends from residue 143-171 and support the topology observed in the crystal structure of vSGLT.
AB - The predicted topology of the mammalian high-affinity sodium/glucose cotransporter (SGLT1), in the region surrounding transmembrane segments 4 and 5, disagrees with the recent published crystal structure of bacterial SGLT from Vibrio parahaemolyticus (vSGLT). To investigate this issue further, 38 residues from I143 to A180 in the N-terminal half of rabbit SGLT1 were each replaced with cysteine and then expressed in COS-7 cells or Xenopus laevis oocytes. The membrane orientations of the substituted cysteines were determined by treatment with the thiol-specific reagent N-Biotinoylaminoethyl methanethiosulfonate (biotin-MTSEA), combined with the membrane impermeant thiol-specific reagent sodium (2-sulfonatoethyl) methanethiosulfonate (MTSES). The present results combined with previous structure/function studies of SGLT1, suggest that transmembrane domain (TM) 4 of mammalian SGLT1 extends from residue 143-171 and support the topology observed in the crystal structure of vSGLT.
KW - Glucose-galactose malabsorption
KW - Methanethiosulfonate reagents
KW - Secondary structure
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U2 - 10.1016/j.bbrc.2008.11.015
DO - 10.1016/j.bbrc.2008.11.015
M3 - Article
C2 - 19013429
AN - SCOPUS:56949087745
SN - 0006-291X
VL - 378
SP - 133
EP - 138
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 1
ER -