Free Access
Reprod. Nutr. Dev.
Volume 44, Number 3, May-June 2004
Page(s) 169 - 181
Reprod. Nutr. Dev. 44 (2004) 169-181
DOI: 10.1051/rnd:2004025

Isolation and characterization of eight pregnancy-associated glycoproteins present at high levels in the ovine placenta between day 60 and day 100 of gestation

Bouchra El Amiria, b, Benoit Remya, Noelita Melo de Sousaa and Jean-François Beckersa

a  Physiology of Reproduction, Faculty of Veterinary Medicine, University of Liege, 4000, Belgium
b  INRA, CRRA de Meknès, BP 578, Morocco

(Received 23 September 2003; accepted 2 February 2004)

Abstract - Pregnancy-associated glycoproteins (PAG), structurally related to aspartic proteinases, are expressed in the outer epithelial cell layer (chorion/trophectoderm) of the ungulate placenta. The aim of the present study was to isolate as many PAG molecules as possible from placentae collected between day 60 and day 100 of gestation and to characterize their amino-terminal amino-acid sequences. Three heterologous radioimmunoassays were used to monitor PAG immunoreactivity throughout the isolation procedures. Sequential use of DEAE-cellulose, gel filtration, and CM ceramic chromatographies led to the isolation of several fractions rich in PAG immunoreactivity. The fractions with a large amount of proteins were also purified by chromatofocusing. The analysis of immunoreactive fractions by SDS-PAGE, Western blotting and two-dimensional electrophoresis followed by amino-terminal microsequencing on PVDF membranes allowed to identify eight different ovPAG with apparent molecular masses ranging from 55 to 66 kDa and isoelectric points from 4.0 to 6.8. The N-terminal sequences were determined and their comparison to those previously identified revealed that four of them are identical to those encoded by previously known cDNA, while the additional four sequences appear to be novel since they have not yet been described.

Key words: ovine / pregnancy-associated glycoprotein / placenta / multiple forms / N-terminal microsequencing

Corresponding author: Jean-François Beckers

© INRA, EDP Sciences 2004