Yeast two hybrid - Trouble with strains

[Martin Gossen]

Dear colleagues,

I am experiencing trouble with the commonly used yeast strains Y190 and
HF7c. Y190 does not seem to have any Histidine selectivity, even when
employing 3-Amino triazole all colonies just grow more slowly (and none
ever were positive in a beta-Gal test). The strain HF7c selects against
Histidine very well but the beta-Gal test is not reproducible (even
strong interactors that I run routinely as positive controls do not make
blue colonies from time to time).

Has anybody experienced similar problems and found a solution?

Thank you in advance,

Martin Gossen
Molecular Human Genetics
Ruhr-University Bochum
Germany

E-mail: martin.gossen at rz.ruhr-uni-bochum.de