Electrophoretic Patterns of Porcine Uterine Protein Secretions during the Estrous Cycle12

Porcine uterine protein secretions collected by flushing uteri of gilts on Days 2–18 and Day 20 of the estrous cycle were studied using acrylamide gel disk electrophoresis. Protein components showed similar electrophoretic patterns on Days 2–11. Beginning on Day 12 there were additional protein bands in an area (Ma/b values of 0.730–0.950) where none had previously been observed. By Days 14–16 there were a total of six protein bands not present on Days 2–11 with Ma/b values of 0.910,0.840, 0.800, 0.740,0.190, and 0.180 when albumin was 1.0000. In addition, a protein having a natural lavender color was present on Days 12–16 which migrated toward the cathode at pH 8.0. The protein bands at 0.840, 0.740 and the lavender protein were PAS-positive. The six protein bands which migrated toward the anode were eluted as a single protein fraction using Sephadex G-200 gel filtration and had an estimated average molecular weight of 20,000. The lavender protein had an estimated molecular weight of 45,000. These data indicate the cyclic nature of porcine uterine protein secretory pattern and provide further characterization of the protein components of porcine uterine secretions.