Part:BBa_K3889024

Human Ovastacin protease

The SAS1B protein or Ovastacin is a member of the astacin family of metalloproteinases. It is a binding partner in the oolemma of oocytes for the intra-acrosomal sperm protein called SLLP1 (Sperm Lysozyme-Like Protein) [1]. In the reproductive system, SAS1B translation is restricted to the tissues at the ovary and oocytes of the reproductive system. It first appears in ovarian follicles during the transition of primary-secondary follicles in the form of zymogen in humans and is released from cortical granules during the cortical reaction in an activated form after getting cleaved[1]. A part of the C-terminal domain of ovastacin remains attached to the oolemma, while the N-terminal active ovastacin domain is secreted [2]. The secreted active protease acts specifically on ZP2 as it is a target for cleavage [3].

Protein Sequence

RLLSAASNKWPMGGSGVVEVPFLLSSKYDEPSRQVILEALAEFERSTCIRFVTYQDQRDFISIIPMYGCFSSVGRSGGMQVVSLAPTCLQKGRGIVLHELMHVLGFWH EHTRADRDRYIRVNWNEILPGFEINFIKSRSSNMLTPYDYSSVMHYGRLAFSRRGLPTITPLWAPSVHIGQRWNLSASDITRVLKLYGCS

Fig 1. Ovastacin (Active site marked in magenta)

C-score	Estimated TM-score	Estimated RMSD
1.83	0.97±0.05	1.8±1.5 Å

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  INCOMPATIBLE WITH RFC[21]

  Illegal XhoI site found at 210
  
• 23
  COMPATIBLE WITH RFC[23]
• 25
  INCOMPATIBLE WITH RFC[25]

  Illegal NgoMIV site found at 479
  
• 1000
  COMPATIBLE WITH RFC[1000]

References

1. Pires, E.S., Hlavin, C., Macnamara, E., Ishola-Gbenla, K., Doerwaldt, C., Chamberlain, C., Klotz, K., Herr, A.K., Khole, A., Chertihin, O., Curnow, E., Feldman, S.H., Mandal, A., Shetty, J., Flickinger, C. and Herr, J.C. (2013), SAS1B protein [ovastacin] shows temporal and spatial restriction to oocytes in several eutherian orders and initiates translation at the primary to secondary follicle transition. Dev. Dyn., 242: 1405-1426. https://doi.org/10.1002/dvdy.24040

2. Körschgen, H., Kuske, M., Karmilin, K., Yiallouros, I., Balbach, M., Floehr, J., Wachten, D., Jahnen-Dechent, W., & Stöcker, W. (2017). Intracellular activation of ovastacin mediates pre-fertilization hardening of the zona pellucida. Molecular human reproduction, 23(9), 607–616. https://doi.org/10.1093/molehr/gax040

3. Anna D. Burkart, Bo Xiong, Boris Baibakov, Maria Jiménez-Movilla, Jurrien Dean; Ovastacin, a cortical granule protease, cleaves ZP2 in the zona pellucida to prevent polyspermy. J Cell Biol 2 April 2012; 197 (1): 37–44. doi: https://doi.org/10.1083/jcb.201112094