comparison with the phosphoprotein patterns of the mutants cyr1-2 ( ts ) and bcy1 , analysed in a previous study , demonstrated not only that the cdc25 gene product is a positive element in the regulation of adenylyl cyclase activity , as suggested by recent studies , but that it is also a negative element in the phosphorylation of a 31 kda protein ( p31c and p31d ) , a protein whose phosphorylation is correlated with cell cycle arrest , and dephosphorylation with cell cycle initiation , respectively .
C0031689
phosphoprotein
C0033684
protein