STRUCTURE AND SIGNIFICANCE OF HUMAN LUTEINIZING HORMONE-BETA CORE FRAGMENT PURIFIED FROM HUMAN PITUITARY EXTRACTS

A fragment of the hCG beta-subunit is present in high concentrations i n the urine of pregnant women and the urine from individuals with ovar ian or other cancers. The utility of immunoreactive measurement of thi s fragment to monitor therapy of such cancers is compromised, however, because high concentrations of the molecule are also detected in the urine of healthy postmenopausal women. It has been suggested that the latter observations may be due to a cross-reacting human (h) LHbeta co re fragment, presumably of pituitary origin, but no such fragment had ever been isolated. We have now isolated a hLHbeta core fragment from a pituitary tissue extract. Its structure is exactly analogous to that of the hCGbeta core fragment. The finding of a discrete hLHbeta core fragment in a tissue extract suggests that it may be produced within p ituitary tissue, rather than by a peripheral degradation process. We h ave also found that the same immunoaffinity method used to extract the hLHbeta core fragment from the pituitary extract purified several pro tein fragments from postmenopausal urine, none of which was related to hLH or hCG. The availability of the pituitary hLHbeta core fragment m ay allow development of assays that distinguish it from its hCG analog .