Critical component of the membrane-bound oxidase of phagocytes that generates superoxide. It is the terminal component of a respiratory chain that transfers single electrons from cytoplasmic NADPH across the plasma membrane to molecular oxygen on the exterior. Also functions as a voltage-gated proton channel that mediates the H(+) currents of resting phagocytes. 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. Interacts with calprotectin (S100A8/9). Interacts with NRROS; the interaction is direct and impairs formation of a stable NADPH oxidase complex. Interacts with CYBC1; CYBC1 may act as a chaperone stabilizing Cytochrome b-245 heterodimer (By similarity). Interacts with NCF2; the interaction is enhanced in the presence of GBP7 (By similarity). The CYBA-CYBB complex interacts with GBP7 (By similarity). As unassembled monomer may localize to the endoplasmic reticulum. Phosphorylated on Ser and Thr residues. Undergoes 'Lys-48'-linked polyubiquitination, likely by RNF145, triggering endoplasmic reticulum-associated degradation. Truncated N-terminus.