L. Hubler et al., CONNECTIONS BETWEEN THE RAS-CYCLIC AMP PATHWAY AND G(1)-CYCLIN EXPRESSION IN THE BUDDING YEAST SACCHAROMYCES-CEREVISIAE, Molecular and cellular biology, 13(10), 1993, pp. 6274-6282
We have identified two processes in the G1 phase of the Saccharomyces
cerevisiae cell cycle that are required before nutritionally arrested
cells are able to return to proliferative growth. The first process re
quires protein synthesis and is associated with increased expression o
f the G1 cyclin gene CLN3. This process requires nutrients but is inde
pendent of Ras and cyclic AMP (cAMP). The second process requires cAMP
. This second process is rapid, is independent of protein synthesis, a
nd produces a rapid induction of START-specific transcripts, including
CLN1 and CLN2. The ability of a nutritionally arrested cell to respon
d to cAMP is dependent on completion of the first process, and this is
delayed in cells carrying a CLN3 deletion. Mating pheromone blocks th
e cAMP response but does not alter the process upstream of Ras-cAMP. T
hese results suggest a model linking the Ras-cAMP pathway with regulat
ion of G1 cyclin expression.