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The primary structure of human apolipoprotein A-IV
Biochimica Et Biophysica Acta
|April 3, 1989
Summary
This study accurately sequenced human apolipoprotein A-IV (apoA-IV) using protein digestion and peptide sequencing. Findings clarify discrepancies with prior DNA-based sequences, suggesting potential sequencing errors or genetic variations.
Area of Science:
- Biochemistry
- Molecular Biology
- Genetics
Background:
- Human apolipoprotein A-IV (apoA-IV) plays a crucial role in lipid metabolism.
- Previous studies reported apoA-IV sequences derived from DNA, but inconsistencies existed.
Purpose of the Study:
- To accurately determine the amino acid sequence of human apoA-IV.
- To resolve discrepancies between protein-derived and DNA-derived apoA-IV sequences.
Main Methods:
- Purification of apoA-IV from chylous ascites fluid.
- Enzymatic digestion (trypsin, S. aureus V8 proteinase) of purified apoA-IV.
- High-performance liquid chromatography (HPLC) for peptide purification.
- Peptide sequencing and comparison with existing DNA-derived sequences.
- Sequencing of apoA-IV cDNA clones.
Main Results:
- The human apoA-IV protein sequence was established, comprising 376 amino acid residues.
- The determined peptide sequence largely agreed with two previously reported DNA-derived sequences.
- Discrepancies were identified in five positions, with the peptide-derived sequence deemed accurate.
- Sequencing errors in prior nucleotide analyses likely explain some discrepancies.
- Potential sequence heterogeneity or cloning artifacts were noted in specific positions.
Conclusions:
- The protein-based sequencing provides an accurate human apoA-IV sequence.
- Discrepancies highlight the importance of validating DNA-derived sequences with protein data.
- Potential for genetic variation or technical artifacts in apoA-IV sequence determination exists.