Homeodomain proteins belong to class ____.
Answers
Answer:
Homeobox genes encode a typical DNA-binding domain of 60 amino acids, known as homeodomain (HD), that characterizes a large family of transcription factors. The homeodomain folds into a characteristic 3D structure containing three alpha-helices, of which the second and third form a helix-turn-helix motif.
Explanation:
Answer:
Explanation:
Homeodomain proteins are DNA-binding proteins that play major roles in many developmental processes of animals as well as fungi and plants. The homeodomain is a protein domain of about 60 amino acids, composed of three alpha helixes that are folded into a compact globular structure that binds DNA.
Helix 2 and helix 3 form a so-called helix-turn-helix (HTH) structure, where the two alpha helices are connected by a short loop region. The N-terminal two helices of the homeodomain are antiparallel and the longer C-terminal helix is roughly perpendicular to the axes established by the first two.
It is this third helix that interacts directly with DNA via a number of hydrogen bonds and hydrophobic interactions, as well as indirect interactions via water molecules, which occur between specific side chains and the exposed bases within the major groove of the DNA.
Proteins containing a homeodomain can regulate the expression of other genes in development and differentiation.