Cloning of the bovine 215-kDa cation-independent mannose 6-phosphate receptor

Area of Science:

• Molecular Biology
• Cell Biology
• Biochemistry

Background:

• The cation-independent mannose 6-phosphate receptor (CI-MPR) is crucial for lysosomal enzyme targeting.
• Understanding the CI-MPR's structure is vital for elucidating its function in cellular trafficking.

Purpose of the Study:

• To identify and characterize cDNA clones encoding a partial sequence of the 215-kDa CI-MPR.
• To analyze the deduced amino acid sequence and structural features of the receptor.

Main Methods:

• Screening a fetal calf liver cDNA library using oligonucleotide probes.
• RNA hybridization analysis to determine mRNA length.
• DNA sequencing to analyze cDNA clones and deduce the amino acid sequence.

Main Results:

• Four overlapping cDNA clones encoding a partial CI-MPR sequence were identified.
• The mRNA is approximately 9.5 kilobases, and the sequenced region spans 4647 nucleotides.
• The deduced polypeptide contains a cytoplasmic domain, a transmembrane segment, and an extracellular domain with eight homologous repeats, including a fibronectin-like segment.

Conclusions:

• The study provides significant insights into the structural organization of the CI-MPR.
• The identified repeats and conserved cysteine-bordered units suggest potential functional importance in receptor activity.