Transcription of

insulin Insulin (, from Latin ''insula'', 'island') is a peptide hormone produced by beta cells of the pancreatic islets encoded in humans by the ''INS'' gene. It is considered to be the main anabolic hormone of the body. It regulates the metabol ...

is regulated by the binding of various

transcription factor In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence. The fu ...

s to the ~400 base pairs before the insulin transcription start site, called the "insulin regulatory sequence". This sequence is made up of several distinct regions with different biochemical properties, each of which serve as binding sites for distinct regulatory proteins. First, multiple A/ T-rich sequences, called "A elements", each of which contains a "TAAT" reocognized by homeodomain proteins. These regions are primarily bound by PDX-1, but also Cdx2 and

Isl-1 Insulin gene enhancer protein ISL-1 is a protein that in humans is encoded by the ''ISL1'' gene. Function This gene encodes a transcription factor containing two N-terminal LIM domains and one C-terminal homeodomain. The encoded protein play ...

. Second, two so-called "C elements" – C1 located 107–118 base pairs before the transcription start site; C2 311–317 base pairs before the start site. C1 is bound by

RIPE3b1 Transcription factor Maf also known as proto-oncogene c-Maf or V-maf musculoaponeurotic fibrosarcoma oncogene homolog is a transcription factor that in humans is encoded by the ''MAF'' gene. Types One type, ''MafA'', also known as ''RIPE3b1'', pr ...

via MafA. C2 (also called the "pancreatic islet cell enhancer sequence" or "PISCES") is bound by

PAX6 Paired box protein Pax-6, also known as aniridia type II protein (AN2) or oculorhombin, is a protein that in humans is encoded by the ''PAX6'' gene. Function PAX6 is a member of the Pax gene family which is responsible for carrying the genet ...

. Third, an "E element" (two in rodents) with sequence GCCATCTG is 91–100 base pairs before the transcription start site and binds the helix-loop-helix transcription factors NEUROD1. Lastly, several "cyclic AMP response elements" with sequence TGACGTCA that binds CREB. In humans, a "Z-element" resides 243–292 base pairs before the start site and binds a complex called ZaI, as well as PDX-1 and MafA.

References

{{Reflist Regulatory sequences