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Protamine inhibits platelet derived growth factor receptor activity but not epidermal growth factor activity
Author(s) -
Huang Jung San,
Nishimura Junji,
Huang Shuan Shian,
Deuel Thomas F.,
Deuel Thomas F.
Publication year - 1984
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.240260402
Subject(s) - protamine , epidermal growth factor , epidermal growth factor receptor , growth factor , chemistry , microbiology and biotechnology , medicine , growth factor receptor , growth factor receptor inhibitor , receptor , cancer research , endocrinology , biology , heparin
Protamine sulfate blocked 125 I‐PDGF binding to its specific physiological receptor on Swiss mouse 3T3 cells. Reduced 125 I‐PDGF binding in the presence of protamine sulfate correlated directly with a protamine sulfate dose‐dependent decrease in the PDGF‐dependent incorporation of [ 3 H]‐thymidine into 3T3 cells and a decreased PDGF‐stimulated tyrosine‐specific protein kinase activity in isolated membrane preparations of 3T3 cells. Protamine sulfate blocked 125 I‐PDGF binding to simian sarcoma virus transformed cells (SSV‐NIH 3T3 and SSV‐NPl cells) and to nontransformed cells in a manner qualitatively identical to unlabelled PDGF. In contrast, protamine sulfate enhanced the specific binding of 125 I‐EGF by increasing the apparent number of EGF receptors on the cell surface. The increase in 125 I‐EGF receptor binding was not prevented by cycloheximide nor by actinomycin D. Protamine sulfate did not affect 125 I‐EGF binding to membranes from 3T3 cells or the EGF‐stimulated 3T3 cell membrane tyrbsinc specific protein kinase activity, suggesting that protamine sulfate may have exposed a population of cryptic EGF receptors otherwise not accessible. Protamine sulfate was fractionated into four active fractions by Sephadex G‐50 gel filtration columns; the half maximum inhibition concentration of 125 I‐PDGF binding to 3T3 cells of protamines I and II (MW ∼ 11,000 daltons and 7,000 daltons, respectively) is ∼ 0.4 μM. Protamine II (MW ∼ 4,800 daltons) was equally active (half maximum inhibition concentration ∼ 0.4 μM); protamine IV (MW ∼ 3,300 daltons) was substantially less active (half maximum inhibition concentration ∼ 2.8 μM). These investigations have extended previous observations that protamine sulfate is a potent inhibitor of PDGF binding and establish that protamine sulfate blocks PDGF binding at the physiological receptor, preventing PDGF initiated biological activities. Protamine sulfate can be used as a reagent to separate the influence of PDGF and EGF on cells with high specificity and has been used to demonstrate that the receptors on simian sarcoma virus transformed 3T3 cells qualitatively respond identically to protamine sulfate as to unlabelled PDGF and are likely identical to those on nontransformed 3T3 cells.