Gene Ontology annotation through association of InterPro records with GO terms
Annotation inferences using phylogenetic trees
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
Purification and characterization of zebrafish hatching enzyme - an evolutionary aspect of the mechanism of egg envelope digestion.
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ZHE1 is the single hatching enzyme of zebrafish; it was purified from hatching liquid, whereas the paralog ZHE2 is rarely expressed.
"one kind of hatching enzyme, ZHE1, was able to be purified from the hatching liquid. Therefore, the hatching of zebrafish embryo is performed by a single enzyme"
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ZHE1 cleaves six sites in the N-terminal regions of the egg-envelope proteins ZP2 and ZP3, outside the ZP domains, partially digesting and swelling the envelope.
"The six ZHE1-cleaving sites were located in the N-terminal regions of egg envelope subunit proteins, ZP2 and ZP3, but not in the internal regions, such as the ZP domains."
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ZHE1 substrate specificity matches medaka HCE (the same sites are cleaved across species), consistent with ZHE1 retaining the ancestral hatching-enzyme character.
"both ZHE1 and MHCE cleaved the same sites of the egg envelope proteins of two species, suggesting that the substrate specificity of ZHE1 is quite similar to that of MHCE"
Crystal structure of zebrafish hatching enzyme 1 from the zebrafish Danio rerio.
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ZHE1 is a zinc metalloprotease; its 1.10 A crystal structure is monomeric and mitten-shaped with the active site in a central cleft.
"Fish hatching enzymes are zinc metalloproteases that digest the egg envelope (chorion) at the time of hatching. The crystal structure of zebrafish hatching enzyme 1 (ZHE1) has been solved at 1.10 Å resolution. ZHE1 is monomeric, is mitten shaped, and has a cleft at the center of the molecule."
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Substrate recognition of the major and minor egg-envelope cleavage sites is determined by distinct residues; Arg182 of ZHE1 salt-bridges the P1' Asp of the major substrate or the P3' Glu of the minor substrate.
"the AspP1' in the major substrate peptide forms a salt bridge with Arg182 of ZHE1, while the GluP3' in the minor substrate peptide instead forms a salt bridge with Arg182"
Species-dependent migration of fish hatching gland cells that express astacin-like proteases in common [corrected].
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Zebrafish hatching-enzyme cDNAs are most similar to medaka HCE and place the enzyme in the astacin protease family; hatching gland cells originate from the polster and in zebrafish settle in the yolk-sac epidermis.
"The predicted amino acid sequences of the cDNA were similar to that of the medaka enzymes, more similar to HCE than to LCE, and it was conjectured that hatching enzymes of zebrafish and masu salmon also belonged to the astacin protease family."
UniProtKB entry Q1LW01 for Danio rerio he1.2
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he1.2 is a metalloendopeptidase that cleaves the N-terminal regions of ZP2 and ZP3 during egg-envelope breakdown at hatching.
"FUNCTION: Metalloendopeptidase which participates in the breakdown of the egg envelope at the time of hatching. Cleaves the N-terminal regions of the zona pellucia glycoproteins ZP2 and ZP3"
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The enzyme is secreted, binds one catalytic zinc, and is expressed in hatching gland cells.
"SUBCELLULAR LOCATION: Secreted"
Falcon deep research report for zebrafish he1.2 (Q1LW01) - hatching enzyme/choriolysin functional annotation
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The report could not confirm a direct literature mapping to Q1LW01 and relies on zebrafish zHE1 and general teleost choriolysin biology; it describes an astacin-like, zinc-dependent, EDTA-inhibitable secreted metalloprotease produced by hatching gland cells that cleaves chorion ZP proteins.
"its activity can be inhibited by chelation of divalent metals (EDTA), consistent with dependence on a catalytic Zn"