Microscale structure analysis of a high-molecular-weight, hydrophobic membrane glycoprotein fraction with platelet-derived growth factor-dependent kinase activity

We investigated the mechanism(s) whereby activation of a growth-factor receptor typically endowed with tyrosine kinase activity, such as the platelet-derived growth factor (PDGF) receptor, triggers phosphoinositide hydrolysis. In Swiss 3T3 cells permeabilized with streptolysin O, an analogue of GTP, guanosine 5′-[gamma-thio]triphosphate, was found to potentiate the coupling of the bombesin receptor to phospholipase C. In contrast, the activation of the enzyme by PDGF occurred in a GTP-independent manner. Moreover, the inactive analogue of GTP, guanosine 5′-[beta-thio]diphosphate, significantly inhibited the bombesin-induced InsP3 generation, whereas it did not decrease the same effect when stimulated by PDGF.

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Prediction of the three-dimensional structures of the nerve growth factor and epidermal growth factor binding proteins (kallikreins) and an hypothetical structure of the high molecular weight complex of epidermal growth factor with its binding protein

Protein Science ◽

10.1002/pro.5560020805 ◽

1993 ◽

Vol 2 (8) ◽

pp. 1229-1241 ◽

Cited By ~ 11

Author(s):

Ben Bax ◽

Geraldine Ferguson ◽

Michael Blaber ◽

Michael J. E. Sternberg ◽

Peter H. Walls

Keyword(s):

Molecular Weight ◽

Nerve Growth Factor ◽

Growth Factor ◽

Epidermal Growth Factor ◽

High Molecular Weight ◽

Binding Proteins ◽

Three Dimensional ◽

High Molecular Weight Complex ◽

Epidermal Growth ◽

Hypothetical Structure

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Involvement of a phosphotyrosine protein phosphatase in the suppression of platelet-derived growth factor receptor autophosphorylation in ras-transformed cells

Biochemical Journal ◽

10.1042/bj2930215 ◽

1993 ◽

Vol 293 (1) ◽

pp. 215-221 ◽

Cited By ~ 9

Author(s):

L Tomáska ◽

R J Resnick

Keyword(s):

Growth Factor ◽

Phosphatase Activity ◽

Receptor Tyrosine Kinase ◽

Protein Phosphatase ◽

Kinase Activity ◽

Platelet Derived Growth Factor ◽

Transformed Cells ◽

Pdgf Receptor ◽

Tyrosine Kinase Activity ◽

Phosphotyrosine Protein Phosphatase

The nature of the suppression of platelet-derived growth factor (PDGF) receptor autophosphorylation in ras-transformed NIH 3T3 fibroblasts was investigated. The PDGF receptor from ras-transformed cells that had been purified by wheatgerm-lectin affinity chromatography displayed normal PDGF-induced autophosphorylation, indicating that the receptor is not irreversibly modified. Various phosphotyrosine-protein-phosphatase inhibitors did not reverse the inhibition of PDGF-receptor kinase in crude membrane preparations from ras-transformed cells. However, treatment of intact ras-transformed cells both with 2 mM sodium orthovanadate and with 20 microM phenylarsine oxide restored PDGF-receptor tyrosine-kinase activity to a level similar to that observed in normal cells. Direct measurement of the phosphatase activities in crude cellular fractions revealed a 2.5-fold higher membrane-associated phosphotyrosine-protein-phosphatase activity in ras-transformed cells, whereas phosphoserine-protein-phosphatase activity remained unchanged between the cell lines. These data suggest that the suppression of the PDGF-receptor tyrosine-kinase activity in ras-transformed cells is mediated via an inhibitory component, distinct from the receptor, that may be positively regulated by the dephosphorylation of tyrosine residue(s).

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