Phagocytosis by neutrophils and other 'professional' phagocytic cells is accompanied by a microbicidal burst of non-mitochondrial respiration.
Cytochrome b-245 is the only clearly defined component of this
oxidase system and its absence provides the molecular basis of
X-linked chronic granulomatous disease (CGD), in which a profound predisposition to
infection results from complete failure of this respiratory burst. Purification of the
cytochrome has proved difficult, with uniform disagreement regarding the identity of its
apoprotein, descriptions of its relative molecular mass (Mr) on SDS-
polyacrylamide gel electrophoresis (PAGE) ranging from 10,000 to 127,000 (10-127K). I report here that it has two subunits, a 23K
protein and the previously described 76-92K
glycoprotein. These subunits are closely linked and remain associated with the
haem of the
cytochrome through affinity and gel filtration chromatography and
sucrose gradient centrifugation, and exhibit a similar distribution in a pH gradient. Neither
protein was detected in the cells of five patients with X-linked CGD whereas both were present in two with the form of this disease with autosomal recessive inheritance.