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Proc Natl Acad Sci U S A September 28, 1999; 96 (20): 11253-8.
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Ovochymase, a Xenopus laevis egg extracellular protease, is translated as part of an unusual polyprotease.

Lindsay LL , Yang JC , Hedrick JL .

Ovochymase, an extracellular Xenopus laevis egg serine active-site protease with chymotrypsin-like (Phe-X) substrate specificity, is released during egg activation. Molecular cloning results revealed that ovochymase is translated as part of an unusual polyprotein proenzyme. In addition to the ovochymase protease domain at the C terminus of the deduced amino acid sequence, two unrelated serine protease domains were present, each with apparent trypsin-like (Arg/Lys-X) substrate specificity, and thus, they were designated ovotryptase1 (at the N terminus) and ovotryptase2 (a mid domain). Also, a total of five CUB domains were interspersed between the protease domains. The presence of a hydrophobic signal sequence indicated that the polyprotein was secreted. Immunolocalization and Western blot studies of all three proteases showed that they are all present in the perivitelline space of unactivated eggs, apparently as proenzymes processed away from the original polyprotein. Western blot analysis also showed that the vast majority of the proteases in ovary, eggs, and embryos were present as the proenzyme forms, suggesting that the functions of these proteases depend on very limited levels of activation.

PubMed ID: 10500163
PMC ID: PMC18020
Article link: Proc Natl Acad Sci U S A
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: bmp1 ovch1 prss1

Article Images: [+] show captions
References [+] :
Bork, The CUB domain. A widespread module in developmentally regulated proteins. 1993, Pubmed