AN APPARENTLY NOVEL PROTEIN OF HUMAN-LEUKOCYTES, REACTIVE WITH AN ANTIBODY TO PROTEIN-KINASE C-GAMMA, IS RAPIDLY MODIFIED UPON CELL ACTIVATION - INITIAL CHARACTERIZATION IN NEUTROPHILS AND THEIR CYTOPLASTS

On immunoblots of human neutrophil cytoplasts (U-CYT), a previously un described 97kDa protein was revealed by intense and selective reaction with an antibody that was initially raised to recognize PKC-gamma. De noted ''gamma-rp'' for gamma-related protein, this acidic cytosolic pr otein somewhat resembled the classic forms of PKC in several biochemic al respects. Appearing as a doublet on low-percentage SDS-PAGE gels, b oth its mobility and staining pattern were rapidly altered by treatmen t of U-CYT with either phorbol ester or chemotactic peptide. Whole neu trophil gamma-rp was detectable only after TCA precipitation of intact cells. It was also detectable in human platelets, lymphocytes, and ne utrophil-like differentiated HL60 cells, but not in fibroblasts, eryth rocytes, monocytes, or monocyte-like differentiated HL60 cells. Our da ta suggest that gamma-rp merits further study as a potential participa nt in cellular activation, and as a possible structural or functional relative of PKC.