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sIL‐6R: more than an agonist?
Author(s) -
Knüpfer Heike,
Preiss Rainer
Publication year - 2008
Publication title -
immunology and cell biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.999
H-Index - 104
eISSN - 1440-1711
pISSN - 0818-9641
DOI - 10.1038/sj.icb.7100113
Subject(s) - glycoprotein 130 , agonist , receptor , microbiology and biotechnology , cytokine , chemistry , ligand (biochemistry) , signal transduction , biology , biochemistry , immunology , stat3
On target cells, interleukin‐6 (IL‐6) interacts with its receptor complex consisting of the membrane‐bound IL‐6 receptor (IL‐6R) and the signal transducing protein gp130. IL‐6R can exist as a soluble protein (sIL‐6R), which binds the ligand IL‐6. This soluble complex can bind to gp130 on cells that lack the membrane‐bound IL‐6R and initiate signaling. This process is named transsignaling. The significance of transsignaling via sIL‐6R is underlined by different publications and exceeds very probably the significance of the membrane‐bound IL‐6R. It is the general assumption that sIL‐6R acts as an agonist in combination with IL‐6 resulting in an enhancement of the IL‐6 effects. In this article, we suppose ‘non‐agonistic’ properties. There are several publications that give reasons to speculate that sIL‐6R (a) has IL‐6‐antagonistic effects, (b) has orphan properties and (c) interacts with yet unknown binding partners different from IL‐6. Knowledge about additional properties of sIL‐6R will enlarge the biologic understanding of this molecule and might give an explanation for the sometimes contrasting effects of the cytokine IL‐6.