CHARACTERIZATION OF EQUINE OVIDUCTAL PROTEINS SYNTHESIZED AND RELEASED AT ESTRUS AND AT DAY 4 AFTER OVULATION IN BRED AND NONBRED MARES

Proteins synthesized and released in vitro by oviducts collected from horse mares during estrus and at day 4 after ovulation for bred and no nbred mares were examined by two-dimensional sodium dodecyl sulfate po lyacrylamide gel electrophoresis (2-D SDS PAGE) and fluorography. Ampu llary and isthmic regions both produced a wide array of nondialyzable proteins in culture. Major proteins or groups of proteins identified a ccording to relative molecular weight (kDa) and apparent isoelectric p oint (pI) were at 100 kDa, pI 8; 100-200 kDa, pI 6; 150 kDa, pI 4.5; 6 0-100 kDa, pI 4; and an array of polypeptides at 21-22 kDa, pI 5-6. Ov iductal secretory activity, measured by incorporation of radiolabeled amino acids into nondialyzable macromolecules released into incubation medium, was greater (P < .01) for the ampullary than the isthmic ovid uctal region. No consistent differences were observed in fluorograms b etween estrus vs. day 4 after ovulation, ampulla vs. isthmus, ipsilate ral vs. contralateral to the corpus luteum or largest follicle, oviduc ts from bred vs. nonbred mares, or mare ages. Dialyzed medium from amp ullary and isthmic regions of oviducts was subjected to 1-D or 2-D SDS PAGE followed by western blotting utilizing an antiserum directed aga inst human retinol binding protein (RBP). The family of 21-22 kDA poly peptides was identified as immunoreactive RBP. (C) 1993 Wiley-Liss, In c.