Microinjection of a Conserved Peptide Sequence of p34$^{cdc2}$ Induces a Ca$^{2+}$ Transient in Oocytes

The product of the yeast cell cycle control gene $cdc$2, and its homologs in higher eukaryotes (p34$^{cdc2}$), all contain a perfectly conserved sequence of 16 amino acids that has not been found in any other protein sequence. Microinjection of this peptide triggers a specific increase in the concentration of intracellular free Ca$^{2+}$ that originates from intracellular stores in both starfish and Xenopus oocytes. Thus, p34$^{cdc2}$ might interact through its conserved peptide domain with some component of the Ca$^{2+}$-regulatory system.