Regulated Endocrine Specific Protein 18 (RESP18)

RESP18 is an 18-kilodalton endocrine-specific transcript whose expression is regulated by a number of different physiological and pharmacological stimuli in different tissues. RESP18 messenger RNA was identified in all cell types in the anterior pituitary, at levels that varied 2-fold from the lowest to the highest; the melanotropes of the intermediate pituitary have levels of RESP18 messenger RNA comparable to the highest levels in cells in the anterior pituitary. Mouse RESP18 was cloned and used as the basis for biosynthetic studies on RESP18 in AtT-20 cells, which express RESP18 endogenously; mouse RESP18 was highly homologous to rat RESP18. RESP18 is a major glucocorticoid-responsive protein in the secretory pathway of corticotropes, but its function may be entirely within the neuroendocrine cell.