HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Calabresi, L. Articles by Franceschini, G. Search for Related Content PubMed PubMed Citation Articles by Calabresi, L. Articles by Franceschini, G. Social Bookmarking                      What's this?

Journal of Lipid Research, Vol. 42, 935-942, June 2001
Copyright © 2001 by Lipid Research, Inc.

Limited proteolysis of a disulfide-linked apoA-I dimer in reconstituted HDL

Correspondence to: Guido Franceschini, at the Center E. Grossi Paoletti, Department of Pharmacological Sciences, Via Balzaretti 9 20133, Milano, Italy., Guido.Franceschini{at}unimi.it (E-mail)

The apolipoprotein A-I_Milano (apoA-I_M) is a molecular variant of apoA-I characterized by the Arg¹⁷³Cys substitution, leading to the formation of homodimers A-I_M/A-I_M. Upon interaction with palmitoyloleoylphosphatidylcholine, A-I_M/A-I_M forms only two species of reconstituted HDL (rHDL) particles, with diameters of 7.8 and 12.5 nm. We used limited proteolysis to analyze the conformation of A-I_M/A-I_M in the two rHDL particles, in comparison with that of apoA-I in rHDL of similar size. ApoA-I in the small, 7.8-nm rHDL is degraded to a greater extent (50% after 6 h) than in the large rHDL (<10% degraded after 6 h). The protease susceptibility of A-I_M/A-I_M in small and large rHDL is instead remarkably the same, with A-I_M/A-I_M being much more sensitive to proteolytic digestion (50% degraded after 10 min) than apoA-I. The identification of the proteolytic fragments by immunoblotting, N-terminal sequencing, and molecular mass determination, shows that the N-terminus of both proteins is resistant to proteolysis, with six cleavage sites located in the central and carboxy-terminal portions of the molecules. Cleavage in the middle of apoA-I occurs at distinct sites in 7.8-nm (Lys¹¹⁸) and 12.7-nm (Arg¹²³) rHDL, indicating a different conformation in small and large rHDL particles. The A-I_M/A-I_M instead adopts a unique and identical conformation in small and large rHDL, with the carboxy-terminal portion of the molecule being remarkably more accessible to the proteases than in apoA-I.

This suggests the presence of a novel carboxy-terminal domain in A-I_M/A-I_M, not organized in a compact structure and not shared by wild-type apoA-I, which may account for the unique functional properties of A-I_M/A-I_M.—Calabresi, L., G. Tedeschi, C. Treu, S. Ronchi, D. Galbiati, S. Airoldi, C. R. Sirtori, Y. Marcel, and G. Franceschini. Limited proteolysis of a disulfide-linked apoA-I dimer in reconstituted HDL. J. Lipid Res. 2001. 42: 935–942.

Supplementary key words: limited proteolysis, protein conformation, apolipoprotein A-I_Milano

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				M. J. Thomas, S. Bhat, and M. G. Sorci-Thomas Three-dimensional models of HDL apoA-I: implications for its assembly and function J. Lipid Res., September 1, 2008; 49(9): 1875 - 1883. [Abstract] [Full Text] [PDF]

				E. Favari, M. Gomaraschi, I. Zanotti, F. Bernini, M. Lee-Rueckert, P. T. Kovanen, C. R. Sirtori, G. Franceschini, and L. Calabresi A Unique Protease-sensitive High Density Lipoprotein Particle Containing the Apolipoprotein A-IMilano Dimer Effectively Promotes ATP-binding Cassette A1-mediated Cell Cholesterol Efflux J. Biol. Chem., February 23, 2007; 282(8): 5125 - 5132. [Abstract] [Full Text] [PDF]

				L. Wang, B. G. Sharifi, T. Pan, L. Song, A. Yukht, and P. K. Shah Bone Marrow Transplantation Shows Superior Atheroprotective Effects of Gene Therapy With Apolipoprotein A-I Milano Compared With Wild-Type Apolipoprotein A-I in Hyperlipidemic Mice J. Am. Coll. Cardiol., October 3, 2006; 48(7): 1459 - 1468. [Abstract] [Full Text] [PDF]

				M. Lee, P. T. Kovanen, G. Tedeschi, E. Oungre, G. Franceschini, and L. Calabresi Apolipoprotein composition and particle size affect HDL degradation by chymase: effect on cellular cholesterol efflux J. Lipid Res., March 1, 2003; 44(3): 539 - 546. [Abstract] [Full Text] [PDF]

				T. G. Cole, W. L. Nowatzke, C. L. Bisgaier, and B. R. Krause Method-dependent Changes in ""HDL-Cholesterol"" with Recombinant Apolipoprotein A-IMilano Infusion in Healthy Volunteers Clin. Chem., April 1, 2002; 48(4): 680 - 681. [Full Text] [PDF]