Cdc25 Background Information The guanine nucleotide exchange factor Cdc25 (also designated Ctn1)
regulates adenylyl cyclase via the small G proteins Ras1 and Ras2 (also known as Glc5 or Ctn5). The yeast Ras proteins regulate cell growth and development by cycling between an active GTP-bound state and an inactive GDP-bound state. Adenylyl cyclase (also designated Cyr1, Hsr1 or Sra4), encoded by the Cdc35 gene, catalyzes the formation of the second messenger cAMP. cAMP exerts its effects via a cAMP-dependent kinase consisting of two regulatory subunits, encoded by Bcy1 (also designated Reg1 or Sra1), and two catalytic subunits, encoded by Tpk1 (also designated Pka1 or Sra3).
