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A Na‐dependent fructose co‐transporter in lobster hepatopancreas
Author(s) -
Ahearn Gregory A.,
Sterling Kenneth M.,
Cheeseman Christopher I.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1202.1
Subject(s) - chemistry , homarus , glucose transporter , biochemistry , transporter , membrane transport , western blot , fructose , microbiology and biotechnology , biology , endocrinology , membrane , gene , insulin , ecology , crustacean
3H‐Fructose (Fru) and 3H‐Glucose (Glc) transport were determined in brush‐border membrane vesicles (BBMV), baso‐lateral membrane vesicles (BLMV) and isolated cells (E, R, F, B) of lobster, Homarus americanus , hepatopancreas (HP). Glc transport was Na‐dependent in BBMV and not affected by a ten‐fold excess of Fru, indicating the presence of an apparent SGLT‐1‐like transporter. Glc uptake by BLMV was facilitative and was not inhibited by a ten‐fold excess of Fru. Fru uptake by BBMV was hyperbolic, Na‐dependent, and not inhibited by Glc. Fru uptake by BLMV was Na‐dependent and not inhibited by Glc. Hepatopancreatic E, F and B cells showed Na‐dependent uptake of Fru, while R cells did not. Na‐dependent Fru uptake by E cells was not inhibited by Glc or mannose (Man). Glucose uptake by E cells was facilitative. Western blot analysis of BBMV, BLMV and E, R, F and B cells with antibodies for mammalian GLUT‐2, GLUT‐4, GLUT‐5, SGLT‐1 and SGLT‐4 indicated the presence of the respective lobster HP orthologous proteins. A GLUT‐2‐like protein (∼50 kD) was present in all four cell types and only in BLMV. A GLUT‐4‐like protein (∼50 kD) was localized to BLMV. A 50 kD, GLUT‐5‐like protein, was present in F and B cells and in BLMV. An SGLT‐1‐like protein (∼75 kD) was detected in R, F and B cells; the signal was strongest in F cells. The SGLT‐1‐like protein was limited to BBMV. An SGLT‐4‐like protein was present in E, R, and F cells; the strongest signal was from E cells. Comparison of Fru and Glc uptake by BBMV, BLMV, and cells, indicated distinct Na‐dependent cotransporters for each sugar. Supported by NSF grant IBN04‐21986.