Part of the receptor for interleukin 6. Binds to IL6 with low affinity, but does not transduce a signal. Signal activation necessitate an association with IL6ST. Activation may lead to the regulation of the immune response, acute-phase reactions and hematopoiesis. Low concentration of a soluble form of IL6 receptor acts as an agonist of IL6 activity.
Isoform 2 is expressed in peripheral blood mononuclear cells and weakly found in urine and serum.
Belongs to the type I cytokine receptor family. Type 3 subfamily. Contains 1 fibronectin type-III domain. Contains 1 Ig-like C2-type (immunoglobulin-like) domain.
The two fibronectin type-III-like domains, contained in the N-terminal part, form together a cytokine-binding domain. The WSXWS motif appears to be necessary for proper protein folding and thereby efficient intracellular transport and cell-surface receptor binding.
A short soluble form may also be released from the membrane by proteolysis.