Structural and functional research of acrosomal proteins

1992 Fiscal Year Final Research Report Summary

• Project/Area Number: 03454018
• Research Category: Grant-in-Aid for General Scientific Research (B)
• Allocation Type: Single-year Grants
• Research Field: 動物発生・生理学
• Research Institution: TOHOKU UNIVERSITY
• Principal Investigator: TAKAGI Takashi Tohoku University, Faculty of Science, Assistant, 理学部, 助手 (00004474)
• Project Period (FY): 1991 – 1992
• Keywords: Acrosomal product / Lysin / meiosis inducing factor / lectin / primary structure / mytilus edulis

Research Abstract

Acrosomal proteins from Mytilus edulis sperm were separated into 11 fractions by a reverse phase HPLC. Among them, three major proteins, named M3, M6 and M7, had strong egg vitelline coat lysin and the first polar body releasing activities. They were present as a monomer and the molecular mass was estimated to be 19 kDa(M3), and 22 kDa(M6 and M7) by SDS-PAGE. The amino acid sequences of these proteins were determined by peptide sequence analysis. The sequence of M7 was confirmed by cDNA sequence analysis and revealed to be synthesized prepro-protein. The mature M6 and M7 proteins were composed of 180 amino acid residues and 76% identical sequence. On the other hand, M3 was composed of 149 amino acid residues and the sequence was different from M6 or M7 (26 % identical), however, positions of six cysteine residues involved in these three proteins were conserved. From the sequence similarity, they seemed to have carbohydrate recognition domain structure of C-type lectin and they really bound to vitelline coats. Thus the mechanism that lysin lyzes vitelline coats by non-enzymatic fashion is that these proteins bind to carbohydrate or carbohydrate-moiety of sugar proteins which consist of membrane and decompose the structure membrane. Decomposition of the membrane or lectin-like activity of M3,M6 and M7 seems to induce the release of the first polar body.