Cloning of Perivitelline Membrane Protein; ZP1 in Turkey (Meleagris gallopavo)

Abstract

In aves, the perivitelline membrane is an extracellular matrix surrounding the oocyte at the time of ovulation, and is composed of several glycoproteins belonging to the zona pellucida (ZP) gene family. ZP1 and ZPC have been identified as the major components of the perivitelline membrane in quail and chicken. In addition, ZPD has been identified as a component of the chicken perivitelline membrane, and is synthesized in ovarian granulosa cells as ZPC. In contrast, ZP1 is synthesized in the liver and transported by blood circulation. In the present study, we isolated complementary DNA of turkey ZP1 from the liver and analyzed the turkey perivitelline membrane and serum using antiserum for quail ZP1. Turkey ZP1 encodes a protein of 943 amino acids containing a signal peptide, glutamine rich repeat, trefoil domain, ZP domain and consensus furin cleavage site, like quail and chicken counterparts. N-glycosylation sites, which have been proposed as important for interaction with sperm, are completely conserved among the birds. Turkey ZP1 shares 93% and 88% sequence identity with quail and chicken ZP1, respectively. In particular, sequence identity of the ZP domain among birds was higher than overall, probably due to the important role of the ZP domain in construction of the perivitelline membrane. Western blot analysis using anti-ZP1 antiserum detected a band which was almost the same molecular mass as quail ZP1, in the lysate of the perivitelline membrane and in the serum of turkey. These results suggest that turkey ZP1 is synthesized in the liver, and is transported by blood circulation to the ovary as reported in quail and chicken.