Related Experiment Videos
Human plasma proapoA-I: isolation and amino-terminal sequence.
Biochemical and Biophysical Research Communications
|June 15, 1983
Summary
Human apolipoprotein A-I (apoA-I) is synthesized as a precursor, proapoA-I. This precursor is secreted and then cleaved into mature apoA-I in human plasma, highlighting a key post-translational modification.
Area of Science:
- Biochemistry
- Molecular Biology
- Protein Chemistry
Background:
- Human apolipoprotein A-I (apoA-I) is a crucial component of high-density lipoproteins.
- ApoA-I is initially synthesized as a 267 amino acid precursor, preproapoA-I.
Purpose of the Study:
- To investigate the processing and forms of apolipoprotein A-I in human circulation.
- To identify the specific precursor form of apoA-I present in human lymph and plasma.
Main Methods:
- Analysis of amino-terminal sequences of apolipoprotein A-I isolated from human thoracic duct lymph.
- Comparison of isolated sequences with nucleic acid sequence analysis of cloned apoA-I.
Main Results:
- Identified a 6-amino acid extension (Arg-His-Phe-Trp-Gln-Gln) at the amino-terminus of apoA-I isolated from lymph, consistent with proapoA-I.
- Confirmed the presence of proapoA-I in human plasma.
- Demonstrated that proapoA-I undergoes post-translational proteolytic cleavage to yield mature plasma apoA-I.
Conclusions:
- ProapoA-I is the secreted precursor form of human apoA-I.
- Post-translational modification of proapoA-I is essential for generating mature apoA-I in plasma.