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Human platelet-derived growth factor. Purification and resolution into two active protein fractions
The Journal of Biological Chemistry
|September 10, 1981
Summary
Human platelets release a growth factor that stimulates cell division and DNA synthesis. This purified platelet-derived growth factor (PDGF) is highly potent, showing activity at very low concentrations.
Area of Science:
- Biochemistry
- Cell Biology
- Molecular Biology
Background:
- Human platelets secrete signaling molecules that influence cellular processes.
- Cellular proliferation and DNA synthesis are fundamental biological activities.
- Growth factors play critical roles in regulating cell behavior.
Purpose of the Study:
- To purify and characterize the factor from human platelets that stimulates DNA synthesis and cell division.
- To determine the biochemical properties and potential relationships between different forms of the purified factor.
Main Methods:
- Purification of the growth factor from human platelets using established biochemical techniques.
- Characterization of the purified factor, including molecular weight determination, amino acid composition analysis, and assessment of glycoprotein nature.
- Assay of the purified factor's ability to stimulate DNA synthesis in cultured human cells.
Main Results:
- A potent mitogenic factor, human platelet-derived growth factor (PDGF), was purified approximately 100,000-fold.
- Two homogeneous fractions, PDGF I (Mr ~31,000) and PDGF II (Mr ~28,000), were isolated and found to be equally active.
- Both fractions exhibited similar basic amino acid compositions with high half-cystine content and were identified as glycoproteins, though differing in carbohydrate composition.
- PDGF demonstrated significant activity in stimulating DNA synthesis at concentrations as low as 0.2 ng/ml.
Conclusions:
- Human platelets secrete a potent growth factor (PDGF) that induces DNA synthesis and cell division in human cells.
- PDGF exists in at least two forms (PDGF I and PDGF II) with similar biochemical properties, suggesting a potential precursor-product relationship or distinct gene products.
- The high potency of purified PDGF highlights its significance in cellular regulation and warrants further investigation into its biological functions and mechanisms of action.