problem in 2-hybrid screen?

Adrienne Horowitz aahorowitz at
Mon Jan 15 13:22:09 EST 1996

tchang at (Tien-Hsien Chang) wrote:
>      A colleague of mine was told by others that a highly basic protein
> used as a bait in the 2-hybrid screen will unavoidably yield numerous unwanted 
> false positives, as it presumably will interact, nonspecifically, with many 
> acidic proteins.  I wonder whether anyone know of this type of rumor (or truth) 
> ?  Thanks in advance for input in this matter.
>                Tien-Hsien Chang
>                Department of Molecular Genetics
>                The Ohio State University


Actually, it is not the highly basic bait proteins that cause false 
positives, rather it is highly acidic bait proteins.  Ruden found that
many yeast transcription factors (including Gal4) require both acidic
and hydrophobic amino acids in their activating regions in order to 
form amphipathic alpha-helices (Ruden 1992 Chromosoma 101:342-348).  
The alpha-helices are thought to be associated with activating 
regions of transcription factors. Some other references you might try:
Ruden et al.  1991 Nature  350(21): 250-252
Ma and Ptashne  1987  Cell 51:113-119
(=)  Adrienne Horowitz
 X   Technical Service Specialist
(=)  CLONTECH Laboratories, Inc.
 X   ph: 800-662-2566 x 1434 
(=)  fx: 415-424-1064
 X   tech at
(=)  aahorowitz at


More information about the Yeast mailing list