title: Is the unique negatively charged polypeptide of crayfish yolk HDL a component of crustacean vitellin?
abstract: The yolk protein of Cherax quadricarinatus contains six major high-density lipoprotein (HDL) subunits with the approximate molecular masses of 177, 155, 106, 95, 86, and 75 kDa, of which only the 106-kDa polypeptide is negatively charged. On the basis of their molecular weights, time of appearance and disappearance, their floating density and susceptibility to enzyme degradation (by a serine proteinase), these six HDL polypeptides were classified into two subgroups. One group comprises the higher-molecular-weight compounds above 106 kDa, and the other includes the lower-molecular-weight compounds up to 95 kDa. Other than being different from the lower-molecular-weight polypeptides, the negatively charged 106-kDa polypeptide was significantly different from members of its higher-molecular-weight group belonging to a different, less abundant, yolk protein as shown by HPLC separation. Immunological studies and peptide mapping in which the 106-kDa polypeptide did not show similarity to any of the other HDL components confirmed these differences. Moreover, the amino acid composition of the 106-kDa polypeptide was different from that of known vitellin from other crustacean species. This unique negatively charged polypeptide presents an enigma as it is known to be a secondary vitellogenic-related HDL polypeptide, immunolocalized in yolk globules; however, it is different to all the other HDL polypeptides, thus presenting the question whether it is indeed a component of "classical" crustacean vitellin.
authors.affiliation: Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel.
authors.forename: U
authors.initials: U
authors.lastname: Abdu
authors.forename: G
authors.initials: G
authors.lastname: Yehezkel
authors.forename: S
authors.initials: S
authors.lastname: Weil
authors.forename: T
authors.initials: T
authors.lastname: Ziv
authors.forename: A
authors.initials: A
authors.lastname: Sagi
mesh_terms: D000818:Animals; D003400:Astacoidea / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D003445:Crustacea / Q000737:chemistry*; D004527:Egg Proteins / Q000737:chemistry*; D005260:Female; D008075:Lipoproteins, HDL / Q000737:chemistry*; D010449:Peptide Mapping; D010455:Peptides / Q000737:chemistry
chemical_list: D004527:Egg Proteins; D008075:Lipoproteins, HDL; D010455:Peptides