Human platelet-derived growth factor. Purification and resolution into two active protein fractions.

TLDR

Human platelets release a factor that induces DNA synthesis and cell division in cultured human cells. Purified PDGF stimulates DNA synthesis at a concentration of 0.2 ng/ml. PDGF was purified 100,000‑fold into two equally active glycoprotein fractions, PDGF I (Mr ≈ 31,000) and PDGF II (Mr ≈ 28,000), which share similar basic amino‑acid compositions with 18 cystine residues but differ in carbohydrate content, suggesting PDGF II may be a proteolytic cleavage product of PDGF I.

Abstract

Human platelets secrete a factor that stimulates cultured human cells to initiate DNA synthesis and to divide. This human platelet-derived growth factor (PDGF) has been purified congruent to 100,000-fold into two equally active homogeneous fractions, PDGF I (Mr congruent to 31,000) and PDGF II (Mr congruent to 28,000). The amino acid compositions of each are similar, highly basic, and show 18 half-cystine residues. Both PDGF I and II are glycoproteins, but differ in their carbohydrate compositions. The data suggest that PDGF II may be a proteolytic cleavage product of PDGF I but do not rule out that the proteins may be separate but very similar gene products. Purified PDGF is active in stimulating DNA synthesis at 0.2 ng/ml.