Known adapters create a defined priming site on a DNA fragment whose original end may not be characterized. This gives PCR one predictable target while a second primer recognizes the sequence of interest. The arrangement connects an unknown or difficult-to-amplify region to a known sequence, allowing selected fragments to be amplified and their boundaries examined.
DNA ligase joins an adapter only when the adapter and DNA fragment have compatible ends. This compatibility controls whether an adapter becomes physically attached and therefore whether the fragment can be amplified by the adapter-specific primer. Ligation consequently links end structure to downstream PCR selection, making adapter attachment a critical early determinant of the products analyzed.
One primer binds the attached adapter, while the other targets the sequence of interest. A fragment is preferentially selected when it contains both the ligated adapter and the targeted sequence arrangement. Repeated thermal cycling then exponentially increases the selected products, producing enough amplified DNA for analysis of fragment structure, genomic location, or sequence-related features.
The workflow begins with DNA fragments that possess ends compatible with the selected adapters. DNA ligase attaches the adapters, after which PCR is performed using an adapter-specific primer together with a primer directed at the sequence of interest. Thermal cycling amplifies the selected products, which can then support mapping, break analysis, restriction-fragment examination, or sequencing preparation.
Researchers can use Ligation-mediated PCR when they need to investigate genomic regions whose ends are undefined or difficult to amplify directly. The method is especially relevant for genomic mapping and detection of DNA breaks, because adapter attachment supplies a known reference point. It also supports analysis of restriction fragments and preparation of DNA for sequencing.
Amplified LM-PCR products can help identify fragment boundaries and characterize complex genomic samples. Because the adapter marks one end while the second primer selects a relevant sequence, the resulting products connect an unknown endpoint with a defined genomic target. This relationship supports interpretation of fragment organization, DNA-break locations, restriction-derived pieces, and sequencing inputs.