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A new type of highly polymerized yolk protein from the cochineal insect Dactylopius confusus
Author(s) -
Ziegler Rolf,
Engler Diane L.,
Bartnek Flash,
Antwerpen Rik Van,
Bluestein Hilary A.,
Gilkey John C.,
YepizPlascencia Gloria M.
Publication year - 1996
Publication title -
archives of insect biochemistry and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.576
H-Index - 66
eISSN - 1520-6327
pISSN - 0739-4462
DOI - 10.1002/(sici)1520-6327(1996)31:3<273::aid-arch3>3.0.co;2-z
Subject(s) - hemolymph , biology , yolk , size exclusion chromatography , polyacrylamide gel electrophoresis , protein subunit , ammonium sulfate precipitation , molecular mass , gel electrophoresis , chromatography , biochemistry , chemistry , enzyme , gene , ecology
A female specific protein was isolated from eggs and female hemolymph of cochineal insects, using density gradient ultracentrifugation, ammonium sulfate precipitation, and size exclusion column chromatography. The protein was found to consist of four different subunits with apparent molecular weights (Mr) 45,000, 49,000, 53,000, and 56,000, respectively. All four subunits were found to be glycosylated; no association of lipids was detected. Size exclusion column chromatography and non‐denaturing polyacrylamide gel electrophoresis demonstrated that the native yolk protein exists as large polymers. Electron microscopy showed that these molecules are long, helical ribbons of variable size which are found in both hemolymph and eggs. Using cryo‐electron microscopy, it was shown that the ribbons were 14.6 ± 1.5 nm wide; the helix they form has a repeat distance of 104.9 ± 11.3 nm and a diameter of 42.1 ± 5 nm. A clear substructure of the ribbons was recognized. The newly identified protein is the major yolk protein of Dactylopius confusus and no other proteins resembling the more familiar vitellins of other insect species were detected. Moreover, the D. confusus yolk protein appears to be unique both in its subunit structure and in its polymerizing qualities. Thus, the cochineal yolk protein (CYP) is suggested to represent a new type of insect yolk protein. © 1996 Wiley‐Liss, Inc.