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Molecular cloning of the mouse 46-kDa mannose 6-phosphate receptor (MPR 46)
A Köster1, G Nagel, K von Figura
1Zentrum Biochemie, Abt. Biochemie II, Universität Göttingen.
Abstract:
A cDNA clone for the mouse 46-kDa mannose 6-phosphate receptor (MPR 46) was isolated from an embryonic mouse cDNA library. Its single open reading frame codes for a protein of 278 residues. It shows an over-all amino-acid identity of 93% with the human receptor. Nine non-conservative amino-acid exchanges are found in the luminal domain, one non-conservative exchange of hydrophobic amino acids is in the transmembrane domain, while the cytoplasmic receptor tails are identical. All five potential N-glycosylation sites are conserved as well as amino acids that are important for ligand binding (Arg 137 and His 131) and disulfide pairing (Cys 32 and 78, Cys 132 and Cys 167, Cys 145 and Cys 179). The absolute identity in the cytoplasmic MPR 46 tail suggests the importance of this amino-acid sequence for the intracellular routing of the MPR 46.
Insights
Researchers isolated a mouse mannose 6-phosphate receptor (MPR 46) cDNA clone, revealing high similarity to the human receptor. The conserved cytoplasmic tail of MPR 46 suggests its crucial role in intracellular routing.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- The mannose 6-phosphate receptor (MPR) family plays a critical role in lysosomal enzyme targeting.
- MPR 46 is a key component involved in intracellular trafficking pathways.
Purpose of the Study:
- To isolate and characterize the cDNA clone for the mouse 46-kDa mannose 6-phosphate receptor (MPR 46).
- To compare the structural features of mouse MPR 46 with its human counterpart.
- To investigate the potential functional implications of conserved regions within the MPR 46 sequence.
Main Methods:
- Isolation of a mouse embryonic cDNA library.
- Sequence analysis of the MPR 46 cDNA clone.
- Amino acid sequence comparison between mouse and human MPR 46.
Main Results:
- A cDNA clone for mouse MPR 46 was successfully isolated, encoding a 278-residue protein.
- Mouse MPR 46 shares 93% overall amino acid identity with human MPR 46.
- Key functional regions, including N-glycosylation sites, ligand-binding residues, and disulfide pairing cysteines, are conserved.
- The cytoplasmic tail of mouse MPR 46 is identical to that of the human receptor.
Conclusions:
- The high conservation of mouse MPR 46, particularly its cytoplasmic tail, highlights its functional importance.
- The identical cytoplasmic tail sequence strongly suggests a critical role in the intracellular routing of MPR 46.
- These findings provide insights into the evolutionary conservation and functional mechanisms of MPR 46.