Molecular cloning of a beta-glucan pattern-recognition lipoprotein from the white shrimp Penaeus (Litopenaeus) vannamei: correlations between the deduced amino acid sequence and the native protein structure.

The hemolymph pattern-recognition beta-glucan binding protein from the white shrimp Penaeus (Litopenaeus) vannamei is also a high density lipoprotein (betaGBP-HDL) involved in innate immunity. The betaGBP-HDL full length cDNA sequence determined was 6.3 kb long, and contains a long 3'UTR region with a polyadenylation signal and a poly-A+ tail. The open reading frame is 1454 amino acids long and the N-terminal residue of the mature protein is localized in position 198 of the ORF. Comparison of the betaGBP-HDL amino acid sequence against GenBank detected only significant similarity to betaGBP from the crayfish Pacifastacus leniusculus. betaGBP-HDL is expressed in hepatopancreas, muscle, pleopods and gills, but not in hemocytes as determined by RT-PCR. We discuss the analysis of the deduced primary sequence in terms of the predicted secondary structure, glucanase-like and RGD motives relevant to its dual roles in defence and lipid transport.