Multiple Cloning Site (MCS)
Definition
A short stretch of synthetic DNA containing a cluster of unique restriction sites, engineered into cloning vectors such as pUC19 and pBlueScript to provide multiple insertion options for foreign DNA.
- Content
- Cluster of unique restriction enzyme sites
- Location
- Engineered into cloning vectors
- Example vectors
- pUC19, pBlueScript
- Purpose
- Multiple options for inserting foreign DNA
- Field
- Molecular cloning
Common questions
Why does a vector need several restriction sites instead of just one?+
Having multiple unique cut sites lets the cloner pick the enzyme pair that matches the ends of whatever DNA fragment they are inserting, and it allows directional cloning by cutting with two different enzymes so the insert can only go in one orientation.
What goes wrong if the insert DNA already contains a site from the MCS?+
Cutting the vector with an enzyme that also cuts inside the insert will fragment the insert itself during ligation, so cloners screen the insert sequence first and choose MCS enzymes that avoid any internal sites in the fragment being cloned.
Related terms
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- Plasmid
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- RFLP (Restriction Fragment Length Polymorphism)
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- Type II Restriction Endonuclease
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