I believe that the original trp1-901 allele originated in Phil Hieter's
laboratory. I recall that it was supplied to several laboratories under
this name and then subsequently renamed trp1-delta1 in the Sikorski and
Hieter (Genetics. 1989. 122:19-27) manuscript. In any case, trp1-901
is a delta, non-reverting allele.
Mike Kladde
PennState University