Complementary DNA for the mouse homolog of the small subunit of human cytochrome b558.

Cytochrome b558, a heterodimeric protein, is considered to be a component of the microbicidal oxidase in phagocytes. We have isolated a cDNA clone for the mouse homolog of the small subunit of human cytochrome b558. Comparison of the predicted amino acid sequence with that of the human protein reveals a high degree of homology (87%). As expected, the mRNA is expressed abundantly in peritoneal neutrophils and, to a lesser extent, in peritoneal macrophages. The transcript is also abundant in the mouse kidney. Although the spleen and small intestine contain considerable amounts of the mRNA, only trace amounts are detected in the brain, liver, testis and heart. The distribution, especially its high expression in the kidney, may suggest another function of the small subunit.