| HOME SCHEDULE AUTHOR INDEX SUBJECT INDEX |
|
(718) IDENTIFICATION OF GLYCODELIN-A (Gd-A) BINDING PEPTIDES USING RANDOM PEPTIDE DISPLAY. Tsang, HY1, Yeung, WSB1, Lee, KF1, 1 Department of Obstetric and Gynaecology, Hong Kong, China ABSTRACT- Glycodelin-A (Gd-A) is a human amniotic fluid-derived glycoprotein with contraceptive and immunosuppressive activities. It is the first endogenous glycoprotein that potently and dose-dependently inhibits binding of human spermatozoa to the zona pellucida. Our previous study showed that 125I-labeled Gd-A and Gd-F (ZIF-1, a new isoform isolated from human follicular fluid) interact with human spermatozoa membrane fraction and form two and three protein complexes, respectively, on a native polyacrylamide gel; whereas, one of the complexes could be displaced by the solubilized zona pellucida proteins. However, the identities of these glycodelins receptor(s) on spermatozoa remain elusive. The aim of this study was to isolate and determine the peptides that can interact with Gd-A. In this study, a screening using a random peptide display library (2x1010cfu/ml) in which dodecapeptide sequences displayed on the E.coli flagellin as fusion proteins was carried out. After five rounds of panning steps, 67 individual clones were selected and their amino acid sequences determined. One of the peptides with sequence PYSGPLAEEFQV, occurs most frequently and extends for 70 % of the total peptides analyzed. Most of these peptides selected from panning were able to interact with GdA in vitro by Western blot and immunoprecipitation analysis. Results from our study shed light on the potential interacting proteins or receptor(s) that interact with Gd-A and allows us to delineate the mechanism of Gd-A/Gd-F action in vitro and in vivo. [The project is partly funded by RGC grants HKU 7188/99M and HKU 7261/01M.] KEY WORDS: human spermatozoa, Glycodelin-A, random peptide display library |
