Purification of the beta-cell glucose-sensitive factor that transactivates the insulin gene differentially in normal and transformed islet cells.

ABSTRACT: The beta cell-specific glucose-sensitive factor (GSF), which binds the A3 motif of the rat I and human insulin promoters, is modulated by extracellular glucose. A single mutation in the GSF binding site of the human insulin promoter abolishes the stimulation by high glucose only in normal islets, supporting the suggested physiological role of GSF in the glucose-regulated expression of the insulin gene. GSF binding activity was observed in all insulin-producing cells. We have therefore purified this activity from the rat insulinoma RIN and found that a single polypeptide of 45 kDa was responsible for DNA binding. Its amino acid sequence, determined by microsequencing, provided direct evidence that GSF corresponds to insulin promoter factor 1 (IPF-1; also known as PDX-1) and that, in additio

SUBMITTER: Marshak S 

PROVIDER: S-EPMC26355 | biostudies-literature | 1996 Dec

REPOSITORIES: biostudies-literature