Characterization of Lipophorin Receptor (LpR) Mediating the Binding of High Density Lipophorin (HDLp) in the Silkworm,Bombyx mori

Abstract

In an earlier report, we described the gene encoding a lipophorin receptor (LpR) of the silkworm, Bombyx mori L. (Lepidoptera: Bombycidae), and recombinant expression of the protein. The present study was performed to characterize the corresponding native BmLpR and its binding characteristics. Polyclonal anti-LpR antibody prepared against the cloned receptor fragment from the cytoplasmic domain specifically detected the receptor. Through immunoblotting, ovary and brain membrane protein samples of BmLpR have shown an apparent molecular mass of 105 kDa and 120 kDa under nonreducing and reducing conditions, respectively. Ligand binding of LpR supported the immunoblot results. It bound to high density lipophorin (HDLp) and has shown requirement of Ca2 in binding. Further, a dose-dependent inhibition by EDTA was observed in receptor ligand binding. The characteristics of the BmLpR protein confirm the properties of a ligand-receptor interaction similar to that of vertebrate low density lipoprotein receptor (LDLR).

Yeast two‐hybrid screen reveals novel protein interactions of the cytoplasmic tail of lipophorin receptor in silkworm brain

“…Both LpR4 and LpR1 have a high-level expression in silkworm brain (Gopalapillai et al, 2006). Unlike LpR1, the identification of native LpR4 protein from silkworm brain has been difficult because of lack of an isoform-specific antibody (Ravikumar et al, 2011). The antibody generated from the 18 specific amino acids of the cytoplasmic domain of LpR4 (Sigma Genosys, Japan), only region divergent from LpR1-3 isoforms, has not been found to be antigenic; it did not detect either the native or recombinant protein of LpR4 in our earlier study (Gopalapillai et al, 2006).…”