Human interleukin-6 (hIL-6) binds to its receptor hIL-6 receptor (hIL-6R), and the resultant hIL-6-hIL-6R complex further binds to human gp130 (hgp130). However, the stoichiometry and assembly of the complex composed of the aforementioned three kinds of molecules have remained elusive, raising the following two questions:

1. Is the complex tetrameric or hexameric?

2. Does hIL-6 bind to hgp130 or not?

So can we determine the stoichiometry and assembly of the protein complex composed of full-length hIL-6-hIL-6R-hgp130 using AFM in solution?

Addendum primum:

I have been unaware of the involvement of hIL-6 in breast cancer. (For multiple myeloma, see here.)

Addendum secundum:

I have found this paper a bit surprising.

Addendum tertium:

Full-length hgp130 has been expressed by using pACSG2.

Addendum quartum:

I have just noticed this paper.