Identification of a novel secretogranin II-derived peptide in the adult and fetal human adrenal gland

Molecular cloning of secretogranin II (SgII) in different species has revea led the existence of a highly conserved 66-amino acid peptide (EM66) flanke d by preserved pairs of basic residues. In the present study we have locali zed and characterized EM66 in the human adrenal gland. A fusion protein con taining the human EM66 peptide was produced in E. coli and used to raise po lyclonal antibodies in rabbits. Immunohistochemical staining of human adren al slices revealed intense labeling of adrenochromaffin cells in the adult and fetal gland. HPLC analysis of adrenal extracts showed the presence of a n immunoreactive peak exhibiting the same retention time as recombinant EM6 6 in both adult and fetus. These data demonstrate that post-translational p rocessing of SgII actually generates a novel peptide in the human adrenal g land. The conservation of the sequence of EM66 in vertebrates and the occur rence of the mature peptide during early ontogenesis of the human adrenal g land strongly suggest that EM66 could exert physiological activities.