omega fragment of Beta-galactosidase

Brian Smith-White smithwhi at
Fri Mar 11 18:23:00 EST 1994

In Article <Jonathan_Kurtis-090394180651 at> "Jonathan_Kurtis at (Jonathan Kurtis)" says:
> I tried mailing this question to Stratagene's new Tech Service email
> account, but have not gotten a response. Could anyone out there please
> answer the following questions:
> 1) does the lacZÆM15 gene on the F' episome in SOLR and XL1-Blue MRF' cells
> code for the omega fragment of Beta-galactosidase ??
lacZ delM15 is the name for a specific mutation of lacZ. If Stratagene has
randomly named some other mutation, then there is a serious problem. Other
wise you can ask the Coli Genetic Stock Center for the nature of that allele.
> 2) if it does, how big is this protein (in Kda) ?
> 3) is it constituativly expressed or is it induced by IPTG?
> The reason for these questions is as follows: I immunoscreened (with a Mab)
> a Lambda ZAP II library and plaque purified a positive clone. I have
> excised the pBluescript SK plasmid into SOLR. When I induce a culture of
> these cells, make an E. coli lysate, and run it out on a gel, I get an
> induced band at 30 Kda that is recognized by my Mab (this is consistent
> with the size of my cDNA insert =1.7 kilobases with some 3' untranslated
> region). I also get an induced band at around 100 kDa (too big to be coded
> for by my insert) that is not recognized by my Mab. I thought that this
> band might be due to the induction of the omega fragment of B-gal.
> Thanks for your help, 
> -- 
> Jonathan Kurtis
> International Health Institute
> Brown University Box G-8033
> Providence, RI  02912

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