Localization of apolipoprotein A-I epitopes involved in the activation of lecithin:cholesterol acyltransferase

J Lipid Res. 1996 Dec;37(12):2557-68.

Abstract

Eight murine monoclonal antibodies (Mab) to apolipoprotein A-I were characterized for their epitopes and for their ability to interfere with lecithin:cholesterol acyltransferase (LCAT) activation mediated by apo apoA-I using a synthetic substrate. Using overlapping synthetic peptides we have identified six continuous epitopes that span amino acids 1-10 (Mab A-I-19), 96-101 (Mab A-I-15), 133-141 (Mab A-I-5), 140-145 (Mab A-I-9), 144-148 (Mab A-I-8), and 167-174 (Mab A-I-57). Furthermore, antibodies A-I-11 and A-I-16 recognized discontinuous epitopes, namely amino acids 124-128 and 144-148. When antibodies were tested for their ability to inhibit LCAT activation, an inhibitory effect was observed with those whose epitopes covered the area of apoA-I encompassing amino acids 96-174. From these data we conclude that several areas of apoA-I spanning the middle region of the apolipoprotein act in concert to stimulate LCAT activity, possibly by cooperative interaction with the enzyme.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apolipoprotein A-I / immunology*
  • Apolipoprotein A-I / metabolism
  • Binding Sites / immunology
  • Enzyme Activation / immunology
  • Epitope Mapping
  • Epitopes / immunology*
  • Humans
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Phosphatidylcholine-Sterol O-Acyltransferase / metabolism*

Substances

  • Apolipoprotein A-I
  • Epitopes
  • Phosphatidylcholine-Sterol O-Acyltransferase