Experimental evidence shows that human IL-12Rbeta2, similar to human IL12Rbeta1, appears to exist at the cell surface as a disulfide bonded dimer/oligomer. Formation of this human Interleukin-12Rbeta2 oligomer is not dependent on Interleukin-12 binding, since it was observed in cells that were never exposed to Interleukin-12 heterodimeric protein.
Interleukin-12 receptor beta1 does not contain any cytoplasmic tyrosine residues, whereas the cytoplasmic region of Interleulin-12 receptor beta2 contains three tyrosine residues. This last has an important role for the beta 2 subunit in Interleukin-12 signal transduction (PMID: 8943050). Based on (Kotenko et. al., 1996, PMID: 8663414) signal transduction receptor chains can be divided into two classes. IL12RB2 would be of the first class : signal transducers (ST) with STAT (or SH2 domain-containg proteins) recruitment sites (SRS) and Jak association sites (JAS) . Whereas IL12RB1 would be the the second class: helper receptors (HR) containg only JAS and no SRS (PMID:27193299 )