ACTIVATION of the superoxide generating system in human neutrophils is thought to involve the interaction or assembly of cytochrome b with other cytosolic and membrane proteins. We have now co-isolated by conventional purification procedures a protein of relative molecular mass 22,000 with cytochrome b. This Ras-related protein is not a fragment of either of the subunits of cytochrome b, and its primary structure, as determined by the sequencing of its complementary DNA, is identical to that predicted from a recently cloned ras- related gene, rap 1 (also termed Krev-1). Immunoaffinity purification on anti-cytochrome and anti-Ras immunoaffinity matrices indicates an association between cytochrome b and the Ras-related protein. The association of a Ras-related GTP-binding protein with cytochrome b of human neutrophils could indicate a role for such a protein in the transduction, regulation or structure of the superoxide generating system.

Original languageEnglish
Pages (from-to)198-200
Number of pages3
Issue number6246
StatePublished - Jan 1 1989


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