Biosynthesis of proHNP and HNP in HNP-1 mice deficient in serglycin or elastase. (A,C,D,F) BM cells were pulsed with ³⁵S-methionine/cysteine for 1 hour and chased for 3 hours. Cell lysates and medium were immunoprecipitated with Abs against proHNP and HNP. Immunoprecipitates were pooled and analyzed by 16% SDS-Tricine-PAGE and fluorography. (A) proHNP and HNP in BM cells (top lane) and chase medium (bottom lane) of wild-type, HNP-1 mice, and HNP-1 mice deficient in serglycin (SG). (B) Ratio of fully processed HNP compared with proHNP in cells and chase medium. (C) proHNP and HNP in normal human BM. (D) proHNP and HNP-1 in HNP-1 mice and HNP-1 mice deficient in SG. After a 3-hour chase, cells were pelleted and medium split in 3 conditions. Two conditions were incubated at 37°C for another 1 or 2 hours, respectively. (E) BM cells were extracted from 2 SG^−/− mice and pooled in chase medium. Cells were split in 2 conditions and purified proHNP was added to one condition and to medium without cells. After 3-hour incubation, cells were pelleted and lysed. Cells and medium were immunoprecipitated with Abs against proHNP and HNP. Precipitates were subjected to SDS-PAGE and immunoblotted for proHNP and HNP. (F) HNP-1 mice and HNP-1 mice deficient in neutrophil elastase (NE).