Different processing of chromogranin B into GAWK-immunoreactive fragments in the bovine adrenal medulla and pituitary gland

Summary Chromogranin B 420–493(GAWK)-like immunoreactivity (chromogranin B (420–493)-LI) was determined by radio-immunoassay using two different rabbit antisera, one raised against chromogranin B (420–436) (GAWK 1–17) (Ab420–436) and the other against chromogranin B 439–457 (GAWK 20–38) (Ab439–457), in bovine and human tissues. Chromogranin B (420–493)-LI was present in the bovine adrenal medulla chromaffin granules as well as in the anterior pituitary gland and was released from the cultured bovine chromaffin cells by stimulation with high K + or nicotine. Chromogranin B (420–493)-LI present in the bovine tissues was detected using Ab420–436 but was not detected using Ab439–457. In the human tissues, chromogranin B (420–493)-LI was detected using Ab420–436 as well as Ab439–457. This suggests that the amino acid sequence of this region (chromogranin B 439–457) is different between human and bovine. On the gel permeation chromatography, chromogranin B (420–493)-LI was eluted at the void volume in the bovine adrenal medulla and at an apparent molecular weight of 4000 in the anterior pituitary gland. On the reverse-phase high-performance liquid chromatography, multiple peaks of chromogranin B (420–493)-LI was detected in the bovine adrenal medulla while one component of chromogranin B (420–493)-LI was found in the anterior pituitary gland. These results suggest that chromogranin B is processed into small fragments of chromogranin B (420–493)-LIs and that this processing is tissue-specific.