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Sequence analysis of cDNAs encoding precursors of starfish asterosaps
M Matsumoto1, A V Briones, T Nishigaki
1Department of Life Science, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan.
Developmental Genetics
|August 10, 1999
Summary
Starfish sperm activating peptides (asterosaps) are synthesized in oocytes from a large precursor with a unique rosary-like structure. This precursor contains multiple asterosap isoforms and requires specific enzymes for maturation.
Area of Science:
- Reproductive biology
- Molecular biology
- Biochemistry
Background:
- Starfish sperm activating peptides (asterosaps) play a crucial role in fertilization.
- Understanding the synthesis of asterosaps is key to comprehending reproductive processes in marine invertebrates.
Purpose of the Study:
- To elucidate the synthesis pathway of starfish sperm activating peptides (asterosaps) within the ovary.
- To characterize the molecular structure of asterosap precursors and their encoding genes.
Main Methods:
- Cloning of cDNAs encoding asterosaps.
- Nucleotide sequence elucidation of asterosap cDNAs.
- Analysis of mRNA expression patterns in oocytes and follicle cells.
Main Results:
- Identified mRNA for asterosaps exclusively in oocytes, with a length of 3.7 kb.
- Discovered multiple asterosap isoforms within cDNA clones.
- Proposed a precursor model: a large prepolypeptide with a "rosary-type" structure of repeating units and spacers, N-terminally rich in glutamine.
- Identified potential cleavage sites (lysine-arginine) for endopeptidases in precursor maturation.
Conclusions:
- Asterosap synthesis is an oocyte-specific process in starfish.
- The unique precursor structure suggests a novel mechanism for generating multiple peptide isoforms.
- Endopeptidase activity is likely involved in processing the asterosap precursor into mature peptides.