Interleukin 11 receptor alpha (IL 11 R alpha, IL 11 R alpha 1) originally designated NR1 in mouse, is a 49 kDa type I transmembrane protein that is a member of the gp130 subfamily of the hematopoietic cytokine receptor family. IL-11 R alpha first binds IL 11 with low affinity, then forms a high affinity receptor when complexed with gp130 homodimers. IL 11 R alpha is also anti-apoptotic for colonic epithelia, and increased IL 11 signaling may be a factor in inflammation-associated gastrointestinal cancer development. The IL11/IL11RA/IL6ST complex may be involved in the control of proliferation and/or differentiation of skeletogenic progenitor or other mesenchymal cells. Essential for the normal development of craniofacial bones and teeth.A soluble form (sIL11RA) can act as an antagonist of IL11-dependent cell differentiation in cells where both transmembrane IL11RA and IL6ST are present.