Taqman

A dual-labeled flourogenic gene-specific probe called a TaqMan probe. This probe is composed of a short (20-25 bases) oligodeoxynucleotide that is labeled with two different flourescent dyes. On the 5' terminus is a reporter dye and on the 3' terminus is a quenching dye. This oligonucleotide probe sequence is homologous to an internal target sequence present in the PCR amplicon. When the probe is intact, energy transfer occurs between the two flourophors and emission from the reporter is quenched by the quencher. During the extention phase of PCR, the probe is cleaved by 5' nuclease activity of Taq polymerase thereby releasing the reporter from the oligonucleotide-quencher and producing an increase in reporter emission intensity.