pp60c-src is a substrate for phosphorylation when cells are stimulated to enter cycle

Area of Science:

• Molecular Biology
• Cell Biology
• Oncogenes

Background:

• The proto-oncogene c-Src (pp60c-src) is an endogenous cellular oncogene product.
• pp60c-src possesses protein kinase activity and is itself a phosphoprotein.

Purpose of the Study:

• To investigate the role of pp60c-src in cell proliferation control.
• To study the phosphorylation of pp60c-src as a substrate during cell cycle entry.

Main Methods:

• Partial purification of pp60c-src using DEAE ion-exchange chromatography.
• Immune precipitation techniques were employed.
• Analysis of pp60c-src phosphorylation in quiescent cells stimulated with serum, platelet-derived growth factor, or 12-O-tetradecanoyl-phorbol-13-acetate.

Main Results:

• A 2-4 fold increase in serine phosphorylation of pp60c-src was consistently observed.
• Phosphorylation levels increased upon stimulation of quiescent cells to enter the cell cycle.

Conclusions:

• pp60c-src phosphorylation is enhanced when cells are stimulated to grow.
• These findings support the hypothesis that pp60c-src plays a role in the regulation of cell proliferation.