Structural and functional studies on biliverdin-associated cyanoprotein from the bean bug, Riptortus clavatus.
Structural and functional analysis were performed on biliverdin-associated cyanoprotein (CP) from the hemolymph (CP-1 to CP-4) and eggs (CPegg, identical to CP-1) of the bean bug, Riptortus clavatus. Isoelectric focusing analysis of purified CPegg and CP-4 revealed that they are composed of a single alpha subunit and a more acidic beta subunit respectively. N-terminal amino acid sequencing revealed that there are six different amino acid residues between the two subunits up to the 29 cycles determined, indicating that they are encoded by different genes. Appreciable sequence similarities in N-terminal region are found between the CP subunits and several insect hexamers. By chemical cross-linking analysis these CPs were demonstrated to have hexameric structures. Two dimensional peptide mapping revealed that alpha and beta subunits share common structures in part and that CP-2 and CP-3 are hybrid molecules bearing both alpha and beta subunits. From these results the molecular structure of CPs was established as follows: CP-1 (CPegg) = alpha 6; CP-2 = alpha 4 beta 2; CP-3 = alpha 2 beta 4; CP-4 = beta 6. In addition, using 125I-labeled CPegg and CP-4, in vivo incorporation into several tissues was examined during the nymphal-adult development. During the late phase of the 5th instar, CP-4 was sequestered preferentially over CPegg by the fat body, while after emergence both proteins were suggested to be incorporated into the newly-formed cuticle. CPegg was sequestered massively by the developing ovaries whereas no appreciable incorporation of CP-4 was observed.
Miura
K
K
Department of Medical Zoology, School of Medicine, Mie University, Tsu, Japan.
Nakagawa
M
M
Chinzei
Y
Y
Shinoda
T
T
Nagao
E
E
Numata
H
H
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D015153:Blotting, Western; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D003432:Cross-Linking Reagents; D004527:Egg Proteins; D006430:Hemiptera / Q000254:growth & development / Q000378:metabolism*; D006458:Hemolymph / Q000378:metabolism; D019476:Insect Proteins; D007525:Isoelectric Focusing; D008675:Metamorphosis, Biological; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D014357:Trypsin
D000596:Amino Acids; C090666:CPegg protein, Riptortus clavatus; D002352:Carrier Proteins; D003432:Cross-Linking Reagents; D004527:Egg Proteins; D019476:Insect Proteins; D014357:Trypsin