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What'sa phagemid? - phagemid cloning (Feb/23/2006 )

At the risk of sounding like a complete amateur, can someone walk me through what a phagemid is, and how one gets a plasmid from it?

Background - I'm looking to buy a gene from cDNA that has already been cloned. My problem is, the mouse variant is only available from one place (that I've found), and only as a "phagemid".

The immediate sources haven't been very helpful - my textbooks have nothing about them, and google/product searches have been a little confusing - some sources seem to say it's just single-stranded DNA in a phage vector, while others imply its an actual phage that requires cotransfection with a helper phage, which then results in plaques bearing double-stranded plasmid.

It's entirely possible I'm way off base on this, so anyone who knows, please enlighten me. Particularly - what exactly is a phagemid, and how do I go about getting bacteria-expressible plasmid from it? (Frame of reference for replies - I've never actually worked with bacteriophage before, all my molecular biology has been done with PCR and restriction digest).


A phagemid is a normal plasmid which additionally has the feature of an M13 origin. The M13 phage origin allows the packaging of the plasmid into an M13 phage when the bacteria is also infected by an M13 helper phage. This was at one time important, because the M13 packaged phage is single stranded, which made it useful in some early types of sequencing reactions. These reactions are now essentially unused, and the utility of M13 phage packaging of phagemids is very limited. You can think of these as just any other plasmid for all intents and purposes.

-phage434- working with phagemid....the name confused me at first but just as phage434 said, it is just another some definition which was useful for me...


Isn't pUC a phagemid?

I do not like this term myself. It serves only to obfuscate as opposed to elucidating the meaning.