CpG islands (CGI) are regions of approximately 1 kb, which colocalise with the origins of DNA replication and with the promoters of about 70% of all genes. CpG Islands reports potential CpG island regions using the method described by Gardiner-Garden and Frommer . The calculation is performed using a. The human genome contains ∼30, CpG islands (CGIs), long stretches (–2 kb) of DNA with unusually elevated levels of CpG.
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Cpg islands Molecular Genetics Trends in Biochemical Sciences Biochemical Society Transactions Seminars in Cell and Developmental Biology Trends in Genetics However, over time methylated cytosines tend to turn into thymines because of spontaneous deamination.
However, due to the rarity of CpGs, it is theorised to be insufficiently effective in preventing a possibly rapid mutation of the dinucleotides. The existence of CpG islands cpg islands usually explained by the existence of selective forces for relatively high CpG content, or low levels of methylation in that genomic area, perhaps having cpg islands do with the regulation of gene expression.
Recently a study showed that most CpG islands are a result of non-selective forces. Inheritance of DNA methylation pattern Any type of cells cpg islands their own methylation pattern so that cpg islands unique set of proteins may be expressed to perform functions specific for this cell type.
Thus, during cell division, the methylation pattern should also pass over to the daughter cell. The existence of CpG islands is usually explained by the existence of selective forces for relatively high CpG content, or low levels of methylation in that genomic area, perhaps having to do with the regulation of gene expression.
Recently a study showed that most CpG islands are a result of non-selective forces. The presence of multiple methylated CpG sites in Cpg islands islands of promoters causes stable silencing of genes.
As Vogelstein et al. The methylation signal is interpreted by proteins capable of binding methylated Cpg islands and of recruiting histone epigenetic modificators, transcriptional corepressors and chromatin remodellers.
UHN Human CpG Island Microarray Database
DNA methylation is essential for mammalian cpg islands, and abnormal methylation patterns have been found in a great variety of human tumour cells. The information contained in methtylated CpGs is interpreted by proteins cpg islands specifically bind to them.
The great majority cpg islands CpG islands colocalise with transcription initiation sites and the origins of DNA replication. CpG islands are differentially methylated in imprinted genes and in the inactive X chromosomes.