IDENTIFICATION AND CHARACTERIZATION OF DENOVO-SYNTHESIZED PORCINE OVIDUCTAL SECRETORY PROTEINS

Oviductal secretory products provide a biochemical environment important for establishment of pregnancy. A previous study identified three de novo-synthesized glycoproteins by one-dimensional SDS-PAGE as well as increased incorporation of [3H]Leu into secretory protein by whole oviduct and ampulla associated with proestrus, estrus, and metestrus only. Here, our objective was to further identify and characterize oviductal secretory proteins, specifically 115 000- and 85 000-M(r) estrus-associated proteins (EAP). Two-dimensional SDS-PAGE resolved the 115 000-M(r) protein into two proteins of 100 000 M(r), one basic and one acidic, and the 85 000-M(r) protein into 75 000- and 85 000-M(r) species (pI < 4.0). Differential secretion of proteins between ampulla and isthmus was indicated. The 100 000-, 75 000-, and 85 000-M(r) proteins were synthesized by ampulla during estrus but not by isthmus nor by uterine endometrium. De novo-synthesized EAP were labeled with glucosamine, Leu, and Met, and the 75 000-85 000-M(r) proteins from ampulla and a 30 000-M(r) family from isthmus were labeled with fucose. Inorganic [35S]sulfate labeled three EAP. Fractionation of culture medium by gel filtration demonstrated differences between products secreted by ampulla and isthmus and suggested that some EAP may be found as high-molecular weight forms in the native state. Results indicate that porcine oviductal tissue synthesizes specific EAP at the time of fertilization and early cleavage-stage embryonic development, that there are differences in the type and distribution of glycoproteins from ampulla and isthmus, and that post-translational modifications occur with the addition of glucosamine, fucose, and inorganic sulfate.