Cloning and expression of the cDNA of chicken cation-independent mannose-6-phosphate receptor.
We cloned and sequenced the 8767-bp full-length cDNA for the chicken cation-independent mannose-6-phosphate receptor (CI-MPR), of interest because, unlike its mammalian homologs, it does not bind insulin-like growth factor II (IGF-II). The cDNA encodes a protein of 2470 aa that includes a putative signal sequence, an extracytoplasmic domain consisting of 15 homologous repeat sequences, a 23-residue transmembrane sequence, and a 161-residue cytoplasmic sequence. Overall, it shows 60% sequence identity with human and bovine CI-MPR homologs, and all but two of 122 cysteine residues are conserved. However, it shows much less homology in the N-terminal signal sequence, in repeat 11, which is proposed to contain the IGF-II-binding site in mammalian CI-MPR homologs, and in the 14-aa residue segment in the cytoplasmic sequence that has been proposed to mediate G-protein-coupled signal transduction in response to IGF-II binding by the human CI-MPR. Transient expression in COS-7 cells produced a functional CI-MPR which exhibited mannose-6-phosphate-inhibitable binding and mediated endocytosis of recombinant human beta-glucuronidase. Expression of the functional chicken CI-MPR in mice lacking the mammalian CI-MPR should clarify the controversy over the physiological role of the IGF-II-binding site in mammalian CI-MPR homologs.
Zhou
M
M
Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, MO 63104, USA.
Ma
Z
Z
Sly
W S
WS
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002645:Chickens / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics; D004705:Endocytosis; D015723:Gene Library; D005966:Glucuronidase / Q000378:metabolism; D006801:Humans; D007335:Insulin-Like Growth Factor II / Q000378:metabolism; D008360:Mannosephosphates / Q000494:pharmacology; D008969:Molecular Sequence Data; D011485:Protein Binding / Q000187:drug effects; D011487:Protein Conformation; D017527:Receptor, IGF Type 2 / Q000096:biosynthesis / Q000235:genetics*; D011994:Recombinant Proteins / Q000096:biosynthesis; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
D018076:DNA, Complementary; D008360:Mannosephosphates; D017527:Receptor, IGF Type 2; D011994:Recombinant Proteins; C027693:mannose-6-phosphate; D007335:Insulin-Like Growth Factor II; D005966:Glucuronidase