Difference between 2 Strain?

Fri Jan 27 14:20:27 EST 1995

Re:  What is the difference between yeast strain ?

Hi There!

I am a newer in yeast but working on the yeast two hybrid system for almost
three years.  A lot of exciting data gave me a big picture about the cross
talking among the proteins I am interested in.  But one interaction bother me
for a while.  I guess this might be a potential problem or could be a
commo-problem in the future using yeast two hybrid system.

1. I detected the interaction between Protein A and Protein B in Yeast strain,
PCY2.  The b-galactosidase activity induced by this interaction is beatiful.

2. Since some other strains have been developed (esp. using his and gal for
double selection), I tried one.  All positive are positive,and all negative are
negative.  Most interaction in my work showed positive.  But A-B interaction
showed negative (both in his and b-galactosidase).

3. I made a conclusion that there is no direct A-B interaction but a complex
containing A and B is formed, and the A-B complex is medicated by other

Above is the experiment and conclusion.  It appears to be perfect to tell this
story in my next publication.  But, as I said, I am an user not a "yeastist". 
So I basically want ask myself and "yeastists" three questions.

1. Is the difference between strains enough to giving these difference? I
understand that the difference between two animal cells might be trillion.  Can
some one tell me at what level the yeast strains show difference?

2. Am I so lucky to find this complex but an indirect interaction by using the 
second strain, which I pick randomly "one day"?  

3. Obiviously, one like to know what is the third factor(s) mediating this
interaction.  Any suggestion to provide that there is such factor(s) before I
screening the yeast library (beacuse the screen is not the first choice, at
least for me)? 

Any suggestion or comments are appreactiated.  If this is a true problem in the
using of two hybrid system, I wish this should be paid attention to.  The
false-positive might means more than what we thought.

By the way, I can read "yeast-net" through gopher.  You can send mail to me or

Thanks again!

Hong F. Wang
Department of Cell Biology, Neurobiology, and Anatomy
University of CIncinnati College of Medicine
231 Bethesda Ave.
Cincinnati, OH 45267-0521

Phone: (513)558-6787
Fax: (513)558-4454
E-mail: wangho at ucbeh.san.uc.edu

More information about the Yeast mailing list