Hox gene is an example of a homeobox gene. The homeobox sequence codes for a 60 amino acid protein domain known as the homeodomain. The main role of homeodomain is to act as a switch that controls gene transcription. See also: Hox gene.
Guanine /ËÉ¡wÉËnÉ¨n/ (G, Gua) is one of the four main nucleobases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, and thymine (uracil in RNA). In DNA, guanine is paired with cytosine. With the formula C 5 H 5 N 5 O, guanine is a derivative of purine, consisting of a fused pyrimidine-imidazole ring system with conjugated double bonds. Being unsaturated, the bicyclic molecule is planar. The guanine nucleoside is called guanosine.
The nitrogen bases form the double-strand of DNA through weak hydrogen bonds. The nitrogen bases, however, have specific shapes and hydrogen bond properties so that guanine and cytosine only bond with each other, while adenine and thymine also bond exclusively.