Isolation of mitotic p34cdc2 apoenzyme from human cells

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• The cdc2 gene product is crucial for cell cycle progression in fission yeast.
• Understanding its human homolog is vital for comprehending human cell division.
• Mitotic regulation involves complex protein interactions and modifications.

Purpose of the Study:

• To develop a method for isolating the human homolog of the cdc2 gene product (p34cdc2) from mitotic cells.
• To characterize the biochemical properties of the purified human p34cdc2.
• To establish a foundation for studying the activation mechanism of human p34cdc2.

Main Methods:

• Cell homogenization and protein isolation techniques.
• Immunological identification using specific antibodies (anti-p34cdc2) and ligands (p13suc1).
• Active-site labeling with [alpha 32P]ATP and phosphorylation assays (casein, histone).
• Detection of tyrosine phosphorylation using anti-phosphotyrosine antibodies.

Main Results:

• A simple procedure successfully isolated human p34cdc2 from mitotic cell homogenates.
• The purified protein was confirmed as the human homolog of p34cdc2.
• Human p34cdc2 was identified as an ATP-binding protein that phosphorylates casein but not histone.
• The purified p34cdc2 exhibited tyrosine phosphorylation, indicating it is in an inactive apoenzyme form.

Conclusions:

• The study successfully isolated and characterized the inactive form of human p34cdc2.
• Purified human p34cdc2 is a valuable reagent for investigating its activation mechanism.
• Further research can elucidate the role of phosphatases in activating p34cdc2 during mitosis.