Reversible calcium-dependent interaction of liposomes with pulmonary surfactant protein A. Analysis by resonant mirror technique and near-infrared light scattering.

The Journal of Biological Chemistry
A MeyboomK P Hofmann

Abstract

Surfactant protein A (SP-A) is crucial for lung function, including tubular myelin formation and lipid uptake by type II pneumocytes. Known properties of SP-A in vitro are its Ca2+-dependent interaction with phospholipids and its role in the aggregation of liposomes. To dissect and to analyze these processes, we have immobilized SP-A and measured binding of liposomes by the resonant mirror technique. Liposome aggregation was followed separately by kinetic light scattering in suspensions. It was found that SP-A-mediated binding and aggregation of liposomes have a common K0.5 of 20 microM for free Ca2+, independent of the species (sheep, rat, or cow) and of the phospholipid composition, and that both reactions exhibit the same high cooperativity (Hill coefficients of 6-9) for Ca2+ ions. However, binding of liposomes to SP-A is >10-fold faster than aggregation. Both processes are completely reversed by low Ca2+ concentrations, but liposomes dissociate from SP-A in <0.3 s, whereas disaggregation of the liposomes takes approximately 30 s. At equilibrium, the level of aggregation depends on the concentration of free SP-A. We interpret these results to be a rapid and reversible sequence of three reactions: (i) a cooperative Ca2+-depen...Continue Reading

References

Jul 1, 1992·The American Journal of Physiology·T B VyasT M Butler
Jul 1, 1991·The American Journal of Physiology·D C KemM B Vallotton
Jan 30, 1991·Biochimica Et Biophysica Acta·R C MacDonaldL R Hu
Apr 1, 1991·The Biochemical Journal·H P HaagsmanW F Voorhout
Jan 1, 1991·Annual Review of Physiology·J R Wright, L G Dobbs
Sep 25, 1990·Biochemistry·H P HaagsmanS Hawgood
Jul 1, 1989·The American Review of Respiratory Disease·Y SuzukiK Kogishi
Aug 1, 1988·Proceedings of the National Academy of Sciences of the United States of America·Y KurokiD R Voelker
Sep 1, 1988·Pediatric Research·D W Nielson, M B Lewis
Feb 1, 1987·Proceedings of the National Academy of Sciences of the United States of America·L G DobbsJ Nellenbogen
Jan 1, 1987·The Journal of Membrane Biology·A Schleicher, K P Hofmann
Apr 1, 1973·The American Journal of Physiology·R J KingJ A Clements
Jan 1, 1984·Experimental Lung Research·R J King

❮ Previous
Next ❯

Citations

May 23, 2001·Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology·N PalaniyarF X McCormack
Feb 16, 1999·Biochimica Et Biophysica Acta·R A RidsdaleG Harauz
Nov 14, 1998·Biochimica Et Biophysica Acta·F X McCormack
Jun 1, 2000·Biochemistry·M L RuanoC Casals

❮ Previous
Next ❯

Related Concepts

Related Feeds

ASBMB Publications

The American Society for Biochemistry and Molecular Biology (ASBMB) includes the Journal of Biological Chemistry, Molecular & Cellular Proteomics, and the Journal of Lipid Research. Discover the latest research from ASBMB here.