alpha 2u-Globulin is present in the rat anterior pituitary

The possibility that the pituitary gland may contain as yet undiscovered regulatory factors is intriguing. Recent reports have suggested the presence, in the anterior pituitary, or a number of proteins of extrapituitary origin. alpha 2u-Globulin, a rat serum and urinary protein, previously shown to be synthesized in the submaxillary gland and in the liver under anterior pituitary control, has now been localized by immunocytochemistry in the cytoplasm of some cells of the anterior pituitary. No alpha 2u-globulin could be detected in either the intermediate or posterior pituitary. The presence of alpha 2u-globulin was confirmed and quantitated by radioimmunoassay. Using RNA blot analysis and cloned alpha 2u-globulin cDNA probes, we could not detect alpha 2u-globulin mRNA sequences in pituitary RNA, indicating that alpha 2u-globulin is not synthesized therein. The presence of alpha 2u-globulin, presumably of circulatory origin, in certain anterior pituitary cells suggests that it may play a role in anterior pituitary function.