title: Cleavage site of a major yolk protein (MYP) determined by cDNA isolation and amino acid sequencing in sea urchin, Hemicentrotus pulcherrimus.
abstract: The overall sequence of cDNA encoding vitellogenin (Vg), a precursor to major yolk protein (MYP), of Hemicentrotus pulcherrimus was determined. Its nucleotide sequence has an open reading frame of 4041 bp encoding 1346 amino acids. The amino acid sequence showed little similarity to other Vgs in vertebrates, insects or nematodes, but resembled members of the vertebrate and invertebrate transferrin family. The N-terminal amino acid sequence of the protein fragments dominant in the later embryonic stage was analyzed in order to determine the cleavage site of MYP. Determination of the cleavage site in MYP and analysis of MYP proteolysis in vitro suggested that MYP has a specific molecular shape to permit its proteolytic fragmentation at a definite site. The functional region of transferrin in MYP is conserved after proteolytic processing. Considering these results and those from other work, the protein called sea urchin Vg is not a true Vg. Therefore, a new name, echinoferrin, is proposed for this protein.
authors.affiliation: Department of Applied Information Technology, Aichi Prefectural University, Nagakute, Aichi 480-1198, Japan. yokota@ist.aichi-pu.ac.jp
authors.forename: Yukio
authors.initials: Y
authors.lastname: Yokota
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Unuma
authors.forename: Akihiko
authors.initials: A
authors.lastname: Moriyama
authors.forename: Keisuke
authors.initials: K
authors.lastname: Yamano
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D018076:DNA, Complementary / Q000032:analysis / Q000302:isolation & purification*; D004527:Egg Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D008969:Molecular Sequence Data; D010053:Ovary / Q000378:metabolism; D012617:Sea Urchins / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D014168:Transferrin / Q000378:metabolism; D014819:Vitellogenins / Q000235:genetics / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D004527:Egg Proteins; D014168:Transferrin; D014819:Vitellogenins