A Novel Glucokinase Regulator in Pancreatic β Cells: PRECURSOR OF PROPIONYL-CoA CARBOXYLASE β SUBUNIT INTERACTS WITH GLUCOKINASE AND AUGMENTS ITS ACTIVITY

Akihiko Shiraishi,Yuichiro Yamada,Yoshiyuki Tsuura,Shimpei Fijimoto,Katsushi Tsukiyama,Eri Mukai,Yukiyasu Toyoda,Ichitomo Miwa,Yutaka Seino

doi:10.1074/jbc.c000530200

Akihiko Shiraishi, Yuichiro Yamada + Show 7 more

Open Access

https://doi.org/10.1074/jbc.c000530200

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Abstract

A glucokinase regulatory protein has been reported to exist in the liver, which suppresses enzyme activity in a complex with fructose 6-phosphate, whereas no corresponding protein has been found in pancreatic beta cells. To search for such a protein in pancreatic beta cells, we screened for a cDNA library of the HIT-T15 cell line with the cDNA of glucokinase from rat islet by the yeast two hybrid system. We detected a cDNA encoding the precursor of propionyl-CoA carboxylase beta subunit (pbetaPCCase), and glutathione S-transferase pull-down assay illustrated that pbetaPCCase interacted with recombinant rat islet glucokinase and with glucokinase in rat liver and islet extracts. Functional analysis indicated that pbetaPCCase decreased the K(m) value of recombinant islet glucokinase for glucose by 18% and increased V(max) value by 23%. We concluded that pbetaPCCase might be a novel activator of glucokinase in pancreatic beta cells.

Highlights

From the ‡Department of Metabolism and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Sakyoku, Kyoto 606-8507 and the ¶Department of Pathobiochemistry, Faculty of Pharmacy, Meijo University, Tempaku-ku, Nagoya 468-8503, Japan
We detected a cDNA encoding the precursor of propionyl-CoA carboxylase ␤ subunit (p␤PCCase), and glutathione S-transferase pull-down assay illustrated that p␤PCCase interacted with recombinant rat islet glucokinase and with glucokinase in rat liver and islet extracts
To clarify whether a glucokinase regulatory protein is present in pancreatic islets, we screened for a cDNA library of the HIT-T15 cell line with the cDNA of glucokinase from rat pancreatic ␤ cells using the yeast two hybrid system and found a novel binding regulator for glucokinase

Summary

Accelerated Publication

A glucokinase regulatory protein has been reported to exist in the liver, which suppresses enzyme activity in a complex with fructose 6-phosphate, whereas no corresponding protein has been found in pancreatic ␤ cells. To search for such a protein in pancreatic ␤ cells, we screened for a cDNA library of the HIT-T15 cell line with the cDNA of glucokinase from rat islet by the yeast two hybrid system. To clarify whether a glucokinase regulatory protein is present in pancreatic islets, we screened for a cDNA library of the HIT-T15 cell line with the cDNA of glucokinase from rat pancreatic ␤ cells using the yeast two hybrid system and found a novel binding regulator for glucokinase

EXPERIMENTAL PROCEDURES

RESULTS

Vmax h

DISCUSSION