Apolipoprotein A-IGiessen (Pro143----Arg). A mutant that is defective in activating lecithin:cholesterol acyltransferase

Eur J Biochem. 1984 Oct 15;144(2):325-31. doi: 10.1111/j.1432-1033.1984.tb08467.x.

Abstract

Apolipoprotein A-IGiessen is a variant form of apo A-I that is displaced from the corresponding normal A-I isoforms on isoelectric focusing gels by a single charge unit towards the cathode [Utermann et al. (1982) J. Biol. Chem. 257, 501-507]. Three subjects heterozygous for the variant were detected in one family. The percentage of the total A-I in plasma represented by the A-IGiessen in these subjects ranged over 25-30%. The variant and normal major A-I isoforms from the proband (Y.J.) were purified by preparative isoelectric focusing and cleaved with CNBr. Analytical focusing of CNBr fragments demonstrated a charge difference between CB3Giessen and normal CB3. Sequence analysis of CB3Giessen revealed that a proline existing in normal A-I was replaced by an arginine in the variant A-I at residue 143. The ability of the mutant A-I to activate purified lecithin:cholesterol acyltransferase was determined in vitro. The cofactor activity of [Arg143]apolipoprotein A-I was about 60-70% of that demonstrated by control A-I. Residue 143 is in a putative beta-turn between two of the repeating amphiphilic helices in apolipoprotein A-I and may be a critical determinant of the protein's structure and function.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Apolipoprotein A-I*
  • Apolipoproteins A / blood*
  • Apolipoproteins A / genetics
  • Chemical Phenomena
  • Chemistry
  • Coenzymes
  • Cyanogen Bromide
  • Electrophoresis / methods
  • Enzyme Activation
  • Humans
  • Hydrolysis
  • In Vitro Techniques
  • Isoelectric Focusing
  • Mutation
  • Phosphatidylcholine-Sterol O-Acyltransferase / metabolism*

Substances

  • Apolipoprotein A-I
  • Apolipoproteins A
  • Coenzymes
  • apolipoprotein A-I Giessen
  • Phosphatidylcholine-Sterol O-Acyltransferase
  • Cyanogen Bromide