HUMAN ENDOMETRIAL PROTEINS WITH CYCLIC CHANGES IN THE EXPRESSION DURING THE NORMAL MENSTRUAL-CYCLE - CHARACTERIZATION BY PROTEIN-SEQUENCE ANALYSIS

Endometrial proteins showing cyclic expression during the normal menst rual cycle were localized on two-dimensional (2-D) electrophoresis gel s separating proteins with isoelectric points (pi) ranging from 3.5 to 7 and relative molecular weights ranging from 10 to 300 kDa. Menstrua l cycle-related proteins were excised from several 2-D gels, concentra ted by one-dimensional (1-D) sodium dodecyl sulphate (SDS)-polyacrylam ide gel electrophoresis, and cleaved in situ by trypsin. The tryptic f ragments were extracted and separated by reverse phase high performanc e liquid chromatography (RP-HPLC). Finally, the partial amino-terminal amino acid sequence of selected tryptic fragments were determined for each protein. We aimed at characterizing the 21 menstrual cycle-relat ed proteins that were visible on silver-stained 2-D electrophoresis ge ls. Of the proteins being maximally synthesized in the proliferative p hase endometrium, we identified proteins associated mainly with the cy toskeleton: vimentins, keratin, tropomyosin and tubulin, but also prot eins such as proliferating cell nuclear antigen and beta-galactoside b inding lectin. The partial amino acid sequences for another two protei ns did not match any protein sequence in the Protein Identification Re source (PIR) and Swissprot databases. In the group of proteins having maximal synthesis in the secretory phase endometrium, we identified cr eatine kinase chain B and an isocitrate dehydrogenase-homologous prote in, both of which are involved in energy metabolism. However, we also identified the annexin IV precursor, the 14-3-3 protein homologue also called stratifin or the epithelial cell marker protein 1 and the 21K tumour protein. Finally, four of the proteins were present in too low amounts to allow characterization. Interestingly, most of the identifi ed proteins have not previously been described as having a menstrual c ycle-related synthesis in the human endometrium. It may be considered that the concentration of some of the cycle-related proteins may be us ed in clinical situations to reflect specific endometrial phases.