GC box
The GC box is a guanine and cytosine- rich regulatory element of eukaryotic transcription ( consensus sequence: GGGCGG ). Molecules required for reading the subsequent gene , the SP1 transcription factors, are attached to this DNA segment in the promoter . These ensure that the RNA polymerase II recognizes the gene to be read and can position itself correctly at the beginning of the gene. The GC box is 60 to 100 nucleotides in front of the start codon .
This form of transcription initiation is relatively typical for gene promoters without a TATA box and without a downstream promoter element (DPE, promoter located below the start of transcription ).
It is not to be confused with the CpG islands , which are much longer at 500–2000 bp and often overlap the promoter area and can even extend into the transcript part. They are statistically richer in CG repeat units than the rest of the genome and arise due to the different methylation in gene areas. GC boxes, on the other hand, are much shorter and have a fairly well-defined space in front of the transcript.
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- Wolfgang Hennig (first), Jochen Graw: Genetics. 4th completely revised edition. Springer-Verlag, Berlin et al. 2006, ISBN 3-540-24096-9 .