Abstract
An ommochrome-binding protein (OBP) from the hemolymph of Manduca sexta has recently been purified and characterized. A cDNA clone was isolated from a fifth instar larval cDNA expression library utilizing antiserum against OBP. Northern blot analysis of total fat body RNA detected a transcript of approximately 1.2 kilobases in fifth instar wandering larvae RNA. The complete nucleotide sequence of the 905-base pair cDNA insert was determined by the dideoxy chain termination method. The OBP cDNA encodes a polypeptide of 274 residues with a predicted molecular weight of 30,580 and with one consensus N-linked glycosylation site. Comparison of the NH2-terminal sequence of the mature protein and the cDNA sequence revealed a typical signal peptide of 18 amino acids. In wandering stage larvae, the OBP transcript appeared to be at least 250-fold less abundant than ribosomal RNA.
Highlights
An ommochrome-binding protein (OBP) from the hemolymph ofManduca sexta has recently been purified and characterized
Itis synthesized by the fatbody, and it occurs in both apoprotein anhdoloprotein forms
During the pupal stage the amount of protein decreases by about 75%,but OBP persists inhemolymph of adults of both sexes (Marteland Law, 1992).Antibodies directedagainstOBP from M. sextu havebeen used to explore thepresence of similar proteins in other insects
Summary
An ommochrome-binding protein (OBP) from the hemolymph ofManduca sexta has recently been purified and characterized. Screeningand Isolation of RecombinantPhage-The antibody against OBP was used to screen a fourth day fifth instar larval fat body cDNA library in vector X Zap I1 (Stratagene), kindly provided by Dr M.
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