The Major Chicken Egg Envelope Protein ZP1 Is Different from ZPB and Is Synthesized in the Liver

Abstract

The extracellular matrix surrounding vertebrate oocytes is called the zona pellucida in mammals and perivitelline membrane (pvm) in birds. We have analyzed this structure in chicken follicles and laid eggs and have identified a 95-kDa component of the pvm, which, by protein sequencing, shows homology to mammalian zona pellucida proteins. Surprisingly, we could not detect this protein in ovarian granulosa cells or oocytes, but instead found high levels in the liver of the laying hen. In contrast, it is absent in rooster liver, but can be efficiently induced by estrogen treatment of the animal. An immunoscreen of a liver λ-ZAP library yielded a cDNA coding for a protein of 934 amino acids. It displayed significant homology to members of the ZP1/ZPB family from other species, notably to mouse and rat ZP1, and was therefore designated chkZP1. It is clearly different from a protein designated chkZPB that had been deposited in the database previously. Alignment of the known members of the ZP1/ZPB family demonstrated the existence of at least three subgroups, with representatives of both the ZP1 and the ZPB sequence homology group occurring in vertebrates. Northern blot analysis of liver extracts revealed the presence of a single 3.2 kb mRNA coding for chkZP1, distinct from the chkZPB transcript detectable in follicles. Immunohistochemical analysis of follicle sections demonstrates that chkZP1 can be found in the blood vessels of the theca cell layer as well as in the pvm surrounding the oocyte. Thus, in the chicken, at least one of the major pvm components is synthesized in the liver, and is transported via the bloodstream to the follicle.2 by guest on

Involvement of interaction of ZP1 and ZPC in the formation of quail perivitelline membrane

“…3a). When the PL lysate was tested with anti-ZP1 antiserum, bands of the 175-kDa and the 97-kDa ZP1 forms were detected (lane 1), a result consistent with evidence from the chicken ZP1 homolog showing that the 190-kDa and the 95-kDa ZP1 are detectable by Western blot analysis in the PL lysate and extracts from the liver of egg-laying hens (Bausek et al 2000). Although the nature of these bands was unclear, the very high molecular weight band and several minor constituents reacted with our anti-ZP1 antiserum were also detected.…”

A duplicated motif controls assembly of zona pellucida domain proteins

“…2 A). Similarly, precursors of avian ZP1 homologues, also secreted by the liver (31,32), terminate with the EHP (Fig. 1B).…”

Identification of a Novel Chondroitin-sulfated Collagen in the Membrane Separating Theca and Granulosa Cells in Chicken Ovarian Follicles

“…2B shows the similarity between the major ZP protein ZP1 (Ref. 19; lanes 1 and 2) and the BM proteins (lanes 3 and 4) from the two avian species. Despite considerable technical difficulty in isolating the BM from the smaller quail follicles, it can be seen that the diffuse band is only slightly larger than ggBM1, and the abovementioned bands at 200 and 165 kDa (lane 3) are present.…”

“…All procedures were performed according to the protocols approved by the Animal Care Committee of the Medical University of Vienna. Rabbit antisera used have been previously described in the indicated references: anti-ggBM1, directed against the SDS-PAGE-isolated major follicle BM component, and anti-chicken perlecan, directed against perlecan LA repeats 2-4 (18), anti-ZP1 (19), anti-chicken apo-VLDLII (20), and anti-chicken apoB-100 (14). Antiserum directed against a 50-kDa apoB-fragment (yB5) present in VLDL isolated from yolk (14) was raised against the gel-eluted protein.…”