Transcription factor required to direct islet cell differentiation during endocrine pancreas development. Specifically required for the differentiation of 4 of the 5 islet cell types and for the production of insulin (, ). Not required for pancreatic PP (polypeptide-producing) cells differentiation. Acts downstream of NEUROG3 and regulates the transcription factors involved in beta-cell maturation and function, thereby restricting the expression of the beta-cell differentiation and specification genes, and thus the beta-cell fate choice. Activates transcription by forming a heterodimer with RFX3 and binding to the X-box in the promoter of target genes . Involved in glucose-stimulated insulin secretion by promoting insulin and L-type calcium channel gene transcription .
Subcellular locations: Nucleus
Expressed in pancreas . Expressed in pancreatic beta-cells (insulin-positive cells) and alpha-cells (glucagon-positive cells) (at protein level). Specifically expressed in pancreas, small intestine and colon . Expressed in endocrine cells in the islets .