Basic helix-loop-helix

Helix-loop - helix transcription factors, a structural motif of DNA binding proteins, which consists of a short α - helix (English loop) is associated with a second longer helix by a flexible loop. This HLH motif differs from the helix-turn- helix motif. Due to the flexibility of the loop, a helix can fold back and lie against a second, so that the two monomers can assemble to form a four-helix bundle and thereby interact both with DNA and with each other.

Lacks a HLH protein is a α -helical extension, which is responsible for interacting with the DNA would then result in the dimerization of such torso protein with an intact protein inactive HLH heterodimers lacking the ability to set to a DNA bind. Torso such proteins in excess to block homodimerization intact so HLH proteins, and thereby prevent binding to the DNA. Thus, the mechanism of heterodimerization of the cell provides a control mechanism for the inactivation of specific gene regulatory proteins.

• Transcription factor
• Protein group