Presence of an 85 kDa pituitary protein (Pit-G) in porcine GH-producing cells

In order to understand the molecular mechanisms responsible for hormone production by the anterior pituitary gland, information about novel molecules and their functions is required. We subjected proteins extracted from porcine pituitary crude nuclei to column chromatography and obtained a protein, Pit-G, with a molecular mass of about 85 kDa. An antibody against Pit-G was raised in a rabbit, and Western blot analysis using this antibody showed that Pit-G was present exclusively in the anterior pituitary gland, double immunocytochemical staining of which revealed that Pit-G-positive cells were localized only in growth hormone (GH)-producing cells. The result also indicated the presence of Pit-G in the cytoplasm. Interestingly, Pit-G was present in a subpopulation of GH-producing cells. We searched the literature for references describing molecular masses and localization of pituitary proteins, but found no information about proteins resembling Pit-G, which suggests that Pit-G is an 85 kDa pituitary protein that plays a specific role in some GH-producing cells.