Antiserum was first purified against the phosphorylated form of the immunizing peptide. The resultant affinity purified antibody was then cross-adsorbed against the non-phosphorylated form of the immunizing peptide.
Mer2 (also known as meiotic recombination 2 protein) is a chromosomal protein that is critical for meiotic recombination and progression. It is phosphorylated at two serine residues, S30 and S271 by the yeast Cdk1 cyclin- dependent kinase homolog. This phosphorylation is S-phase specific, and thus has the potential to be a specific assay for S-phase cyclin-dependent kinases. Moreover, there are hints that the phosphorylation may be a mark of replication fork passage, which would indicate that Sphase CDK associates with the replication fork.