Critical component of the membrane-bound oxidase of phagocytes that generates superoxide. Associates with NOX3 to form a functional NADPH oxidase constitutively generating superoxide. Composed of a heavy chain (beta) and a light chain (alpha). Component of an NADPH oxidase complex composed of a heterodimer formed by the membrane proteins CYBA and CYBB and the cytosolic subunits NCF1, NCF2 and NCF4. Interacts with NCF1 (via SH3 domain). Interacts with SH3PXD2A (By similarity). Interacts with DUOX1, DUOX2 and TPO. Interacts with NOX3 and NOX4. Interacts with calprotectin (S100A8/9) (By similarity). Interacts with GBP7 (By similarity). As unassembled monomer may localize to the endoplasmic reticulum. Expressed to a relatively high level in kidney, spleen, thymus and lung, and to a lower level in aorta, adrenals, and heart. Expression is not detected in liver or brain. The heme prosthetic group could be coordinated with residues of the light chain, the heavy chain, or both, and it is possible that more than one heme is present per cytochrome b-245. Phosphorylation at Thr-147 enhances NADPH oxidase activity by promoting p47phox binding. Ubiquitinated at Lys-149 likely by RNF145. Belongs to the p22phox family.