Is the unique negatively charged polypeptide of crayfish yolk HDL a component of crustacean vitellin?
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.
Abdu
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Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel.
Yehezkel
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Weil
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Ziv
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Sagi
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A
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
D004527:Egg Proteins; D008075:Lipoproteins, HDL; D010455:Peptides