Purification of a sulfated secretory protein from the adenohypophysis. Immunochemical evidence that similar macromolecules are present in other glands.

A sulfated secretory protein (apparent molecular weight approximately 70 000; isoelectric point approximately 4.8) recently identified as a minor component of mammotroph granules [21] has been purified, by ion-exchange chromatography on DEAE-Sephadex followed by preparative slab gel electrophoresis, from homogenates of bovine anterior pituitary glands pulse-labeled with [35S] sulfate. The homogeneity of the final product was established by one-dimensional as well as by two-dimensional gel electrophoresis followed by fluorography to reveal labeled polypeptides. Specific antibodies were generated against the purified protein. Immunodiffusion and radioimmuno-labeling of polyacrylamide gels revealed that proteins immunologically related to the adenohypophyseal sulfated component, exist in other glands, such as the neurointermediate pituitary and adrenal medulla. We envisage the possibility that the adenohypophyseal sulfated component belongs to a family of proteins which might play a widespread, though not general role in the secretory process.