Receptor for interleukin-12. This subunit is the signaling component coupling to the JAK2/STAT4 pathway. On IL12 stimulation, enhances IFN-gamma expression. Heterodimer/heterooligomer; disulfide-linked. The functional high affinity IL12 receptor is composed of I12RB1 and IL12RB2. Il12RB2 binds JAK2 (via its N-terminal) through a membrane-proximal region of the cytoplasmic domain (By similarity). The WSXWS motif appears to be necessary for proper protein folding and thereby efficient intracellular transport and cell-surface receptor binding. The box 1 motif is required for JAK interaction and/or activation. On IL12 stimulation, phosphorylated on C-terminal tyrosine residues. Belongs to the type I cytokine receptor family. Type 2 subfamily.