gp130 dimerization in the absence of ligand: preformed cytokine receptor complexes.
It is established that cytokine receptors signal after ligand binding as homo- or hetero-dimers in heteromeric complexes, but it is unclear, when dimerization occurs. To investigate gp130 dimerization, we performed co-precipitation experiments with the endogenous cytokine receptors gp130 and leukemia inhibitory factor receptor (LIF-R) and with gp130 variants carrying two different C-terminal peptide tags. Furthermore, fluorescence resonance energy transfer (FRET) was employed to detect dimerization of two fluorescent-tagged gp130 variants. Confocal laser scanning microscopy was used for FRET detection in live cells. gp130 and LIF-R could be coprecipitated in the absence of ligand. The interaction, however, was intensified by the addition of LIF. Similar results were obtained with the gp130 variants and confirmed by FRET analysis in live cells. The present study clearly demonstrates the existence of preformed but inactive gp130/LIF-R hetero- and gp130/gp130 homo-dimers. The addition of ligand enhanced the respective dimer formation and was required for signal transduction.
Tenhumberg
Stephanie
S
Department of Biochemistry, Christian Albrechts University Kiel, Olshausenstrasse 40, D-24098 Kiel, Germany.
Schuster
Björn
B
Zhu
Lixin
L
Kovaleva
Marina
M
Scheller
Jürgen
J
Kallen
Karl-Josef
KJ
Rose-John
Stefan
S
D000818:Animals; D002460:Cell Line; D002522:Chlorocebus aethiops; D050822:Cytokine Receptor gp130 / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D053680:Leukemia Inhibitory Factor Receptor alpha Subunit; D008024:Ligands; D011485:Protein Binding; D018121:Receptors, Cytokine / Q000235:genetics / Q000378:metabolism; D053606:Receptors, OSM-LIF
C507840:LIFR protein, human; D053680:Leukemia Inhibitory Factor Receptor alpha Subunit; D008024:Ligands; D018121:Receptors, Cytokine; D053606:Receptors, OSM-LIF; D050822:Cytokine Receptor gp130