Analysis of proteins secreted by the human endometrium in vivo and in vitro.

Abstract

Human uterine luminal fluids contain over two dozen proteins distinct from those of serum as detected by two dimensional gel electrophoresis and silver-type protein staining. Eighty-one percent of these uterine fluid proteins can be detected in vitro by radiolabeled methionine incorporation studies and the vast majority of these products are epithelial in origin. The major recognizable menstrual cycle phase-dependent change in the protein pattern in these gels was the appearance of a protein group (number 27) of approximately 25,000 mw and pI of 5.8 - 6.3. This group of proteins was found in nearly all mid- and all late secretory phase fluids or culture media and in none obtained earlier in the cycle. As yet, however, it has not been possible to induce these proteins in proliferative specimens in vitro by the addition of estrogens and/or progestins, though studies along these lines are continuing. Although we cannot be certain, it appears as though protein group number 27 is distinct from, but similar in several respects to, other proteins of human endometrium reported in the literature.