omega fragment of Beta-galactosidase

Jonathan Kurtis Jonathan_Kurtis at
Wed Mar 9 18:10:09 EST 1994

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 ??

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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