Zona Pellucida Proteins, Fibrils, and Matrix

2020 ◽  
Vol 89 (1) ◽  
pp. 695-715
Author(s):  
Eveline S. Litscher ◽  
Paul M. Wassarman

The zona pellucida (ZP) is an extracellular matrix that surrounds all mammalian oocytes, eggs, and early embryos and plays vital roles during oogenesis, fertilization, and preimplantation development. The ZP is composed of three or four glycosylated proteins, ZP1–4, that are synthesized, processed, secreted, and assembled into long, cross-linked fibrils by growing oocytes. ZP proteins have an immunoglobulin-like three-dimensional structure and a ZP domain that consists of two subdomains, ZP-N and ZP-C, with ZP-N of ZP2 and ZP3 required for fibril assembly. A ZP2–ZP3 dimer is located periodically along ZP fibrils that are cross-linked by ZP1, a protein with a proline-rich N terminus. Fibrils in the inner and outer regions of the ZP are oriented perpendicular and parallel to the oolemma, respectively, giving the ZP a multilayered appearance. Upon fertilization of eggs, modification of ZP2 and ZP3 results in changes in the ZP's physical and biological properties that have important consequences. Certain structural features of ZP proteins suggest that they may be amyloid-like proteins.

Author(s):  
David A. Agard ◽  
Yasushi Hiraoka ◽  
John W. Sedat

In an effort to understand the complex relationship between structure and biological function within the nucleus, we have embarked on a program to examine the three-dimensional structure and organization of Drosophila melanogaster embryonic chromosomes. Our overall goal is to determine how DNA and proteins are organized into complex and highly dynamic structures (chromosomes) and how these chromosomes are arranged in three dimensional space within the cell nucleus. Futher, we hope to be able to correlate structual data with such fundamental biological properties as stage in the mitotic cell cycle, developmental state and transcription at specific gene loci.Towards this end, we have been developing methodologies for the three-dimensional analysis of non-crystalline biological specimens using optical and electron microscopy. We feel that the combination of these two complementary techniques allows an unprecedented look at the structural organization of cellular components ranging in size from 100A to 100 microns.


Reproduction ◽  
2004 ◽  
Vol 127 (4) ◽  
pp. 417-422 ◽  
Author(s):  
Tanya Hoodbhoy ◽  
Jurrien Dean

The zona pellucida surrounding the egg and pre-implantation embryo is required for in vivo fertility and early development. Explanatory models of sperm–egg recognition need to take into account the ability of sperm to bind to ovulated eggs, but not to two-cell embryos. For the last two decades, investigators have sought to identify an individual protein or carbohydrate side chain as the ‘sperm receptor’. However, recent genetic data in mice are more consistent with the three-dimensional structure of the zona pellucida, rather than a single protein (or carbohydrate), determining sperm binding. The mouse and human zonae pellucidae contain three glycoproteins (ZP1, ZP2, ZP3) and, following fertilization, ZP2 is proteolytically cleaved. The replacement of endogenous mouse proteins with human ZP2, ZP3 or both does not alter taxon specificity of sperm binding or prevent fertility. Surprisingly, human ZP2 is not cleaved following fertilization and intact ZP2 correlates with persistent sperm binding to two-cell embryos. Taken together, these data support a model in which the cleavage status of ZP2 modulates the three-dimensional structure of the zona pellucida and determines whether sperm bind (uncleaved) or do not (cleaved).


1995 ◽  
Vol 310 (2) ◽  
pp. 507-516 ◽  
Author(s):  
Y Zeng ◽  
C Weiss ◽  
T T Yao ◽  
J Huang ◽  
L Siconolfi-Baez ◽  
...  

Bovine NAD(+)-dependent isocitrate dehydrogenase was shown previously to contain four subunits of approx. 40 kDa (subunits 1-4) possessing different peptide maps and electrophoretic properties [Rushbrook and Harvey (1978) Biochemistry 17, 5339-5346]. In this study the heterogeneity is confirmed using enzyme purified by updated methods and from single animals, ruling out allelic variability. Subunits 1 and 2 were differentiated from each other and from subunits 3 and 4 by N-terminal amino acid sequencing. Subunits 3 and 4 (subunits 3/4) were identical in sequence over 30 residues. The N-terminal residues of subunits 1 and 2 were homologous but not identical with the beta- and gamma-subunits respectively of the comparable pig heart enzyme. Subunits 3/4 were identical over 30 residues with the N-terminus of the pig heart alpha-subunit. Full-length sequence, including that for mitochondrial import, is presented for a protein with the processed N-terminus of subunits 3/4, deduced from cloned cDNA obtained utilizing the N-terminal sequence information. The derived amino acid sequence for the mature protein contains 339 amino acids and has a molecular mass of 36,685 Da. Complete identity with N-terminal and Cys-containing peptides totalling 92 residues from the alpha-subunit of the pig heart enzyme [Huang and Colman (1990) Biochemistry 29, 8266-8273] suggests that maintenance of a particular three-dimensional structure in this subunit is crucial to the function of the enzyme. An electrophoretic heterogeneity within the pig heart alpha-subunit, similar to that shown by bovine subunits 3/4, was demonstrated. One reordering of the Cys-containing peptides of the pig heart alpha-subunit is indicated. Sequence comparison with the distantly related NADP(+)-dependent enzyme from Escherichia coli, for which the three-dimensional structure is known [Stoddard, Dean and Koshland (1993) Biochemistry 32, 9310-9316] shows strong conservation of residues binding isocitrate, Mg2+ and the NAD+ moiety of NADP+, consistent with a catalytic function.


Author(s):  
Marco A. Riojas ◽  
Andrew M. Frank ◽  
Nikhita P. Puthuveetil ◽  
Beth Flores ◽  
Michael Parker ◽  
...  

AbstractThe function of the SARS-CoV-2 accessory protein p6, encoded by ORF6, is not fully known. Based upon its similarity to p6 from SARS-CoV, it may play a similar role, namely as an antagonist of type I interferon (IFN) signaling. Here we report the sequencing of a SARS-CoV-2 strain passaged six times after original isolation from a clinical patient in Hong Kong. The genome sequence shows a 27 nt in-frame deletion (Δ27,264-27,290) within ORF6, predicted to result in a 9 aa deletion (ΔFKVSIWNLD) from the central portion of p6. This deletion is predicted to result in a dramatic alteration in the three-dimensional structure of the resultant protein (p6Δ22-30), possibly with significant functional implications. Analysis of the original clinical sample indicates that the deletion was not present, while sequencing of subsequent passages of the strain identifies the deletion as a majority variant. This suggests that the deletion originated ab initio during passaging and subsequently propagated into the majority, possibly due to the removal of selective pressure through the IFN-deficient Vero E6 cell line. The specific function of the SARS-CoV-2 p6 N-terminus, if any, has not yet been determined. However, this deletion is predicted to cause a shift from N-endo to N-ecto in the transmembrane localization of the SARS-CoV-2 p6Δ22-30 N-terminus, possibly leading to the ablation of its native function.


1989 ◽  
Vol 257 (2) ◽  
pp. 247-253 ◽  
Author(s):  
Giuseppe Familiari ◽  
Stefania A. Nottola ◽  
Antonio Familiari ◽  
Pietro M. Motta

2014 ◽  
Vol 898 ◽  
pp. 318-321 ◽  
Author(s):  
Xin Hui Wang ◽  
Lin Sang ◽  
Zhi Yong Wei ◽  
Li Jie Zhai ◽  
Min Qi

Sponge-like scaffold with a specific three-dimensional structure resembling the actual extracellular matrix of a particular tissue show significant potential for the regeneration and repair of damaged anisotropic tissues. In this research, an oriented microtubular P34HB scaffold was prepared successfully. The mechanical property showed that anisotropy of modulus is much greater than a typical non-oriented scaffold. Altering the P34HB concentration allowed P34HB scaffolds to be produced with complex pore orientations, and anisotropy in pore size and alignment.


2006 ◽  
Vol 69 (6) ◽  
pp. 415-426 ◽  
Author(s):  
Giuseppe Familiari ◽  
Michela Relucenti ◽  
Rosemarie Heyn ◽  
Giulietta Micara ◽  
Silvia Correr

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