Molecular characterization of the VLDL receptor homolog mediating binding of lipophorin in oocyte of the mosquito Aedes aegypti.
Lipophorin (Lp) functions as a yolk protein precursor in the mosquito Aedes aegypti and it is internalized via receptor-mediated endocytosis (Insect Biochem. Mol. Biol., 30 (2000) 1161). We cloned and molecularly characterized a putative mosquito ovarian lipophorin receptor (AaLpRov) cDNA. The cDNA has a length of 3468 bp coding for a 1156-residue protein with a predicted molecular mass of 128.9 kDa. The deduced amino acid sequence of the cDNA revealed that it encodes a protein homolog of the LDL receptor superfamily, and that it harbors eight cysteine-rich ligand binding repeats at the N-terminus like vertebrate VLDL receptors. The deduced amino acid sequence of this mosquito ovarian receptor is most similar to that of the locust lipophorin receptor (LmLpR) (64.3%), and is only distantly related to the mosquito vitellogenin receptor (VgR) (18.3%), another ovarian LDLR homolog with a different ligand. The AaLpRov cDNA was expressed in a TnT Coupled Reticulocyte Lysate system, and co-immunoprecipitation experiments confirmed that the receptor protein specifically binds Lp. Developmental expression profiles clearly showed that AaLpRov transcripts are present in the vitellogenic ovary, with peak expression at 24-36 h post blood meal. In situ hybridization indicated that AaLpRov transcripts are present only in female germ line cells. Distance-based phylogenetic analyses suggest that the insect LpR and vertebrate LDL/VLDL receptor lineages separated after divergence from the insect VgR lineage.
Cheon
H M
HM
Division of Life Science, College of Natural Sciences, Gyeongsang National University, Chinju 660-701, Gyeongnam, South Korea.
Seo
S J
SJ
Sun
J
J
Sappington
T W
TW
Raikhel
A S
AS
D000330:Aedes / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000378:metabolism*; D018076:DNA, Complementary; D004527:Egg Proteins / Q000378:metabolism; D005260:Female; D006801:Humans; D019476:Insect Proteins / Q000378:metabolism*; D008074:Lipoproteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D016366:Open Reading Frames; D018160:Receptors, Cytoplasmic and Nuclear / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D011973:Receptors, LDL / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D002352:Carrier Proteins; D018076:DNA, Complementary; D004527:Egg Proteins; D019476:Insect Proteins; D008074:Lipoproteins; D018160:Receptors, Cytoplasmic and Nuclear; D011973:Receptors, LDL; C036053:VLDL receptor; C032830:lipophorin; C432945:lipophorin receptor