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Hydrophobic Pulmonary Surfactant Proteins SP-B and SP-C Induce Pore Formation in Planar Lipid Membranes: Evidence for Proteolipid Pores
- Source :
- Repositori Universitat Jaume I, Universitat Jaume I
- Publication Year :
- 2013
- Publisher :
- Elsevier BV, 2013.
-
Abstract
- Pulmonary surfactant is a complex mixture of lipids and specific surfactant proteins, including the hydrophobic proteins SP-B and SP-C, in charge of stabilizing the respiratory surface of mammalian lungs. The combined action of both proteins is responsible for the proper structure and dynamics of membrane arrays in the pulmonary surfactant network that covers the respiratory surface. In this study, we explore the possibility that proteins SP-B and SP-C induce the permeabilization of phospholipid membranes via pore formation. To this end, electrophysiological measurements have been carried out in planar lipid membranes prepared with different lipid/protein mixtures. Our main result is that channel-like structures are detected in the presence of SP-B, SP-C, or the native mixture of both proteins. Current traces show a high variety of conductance states (from pS to nS) that are dependent both on the lipid composition and the applied potential. We also show that the type of host lipid crucially determines the ionic selectivity of the observed pores: the anionic selectivity observed in zwitterionic membranes is inverted to cationic selectivity in the presence of negatively charged lipids. All those results suggest that SP-B and SP-C proteins promote the formation of proteolipid channels in which lipid molecules are functionally involved. We propose that proteolipidic membrane-permeabilizing structures may have an important role to tune ionic and lipidic flows through the pulmonary surfactant membrane network at the alveolar surfaces.
- Subjects :
- Anions
Lung surfactant
Channel conductance
Proteolipids
Membrane lipids
Lipid Bilayers
Sus scrofa
Phospholipid membranes
Biophysics
Pulmonary surfactant
Animals
Selectivity
Pulmonary surfactant-associated protein B
Lipid bilayer phase behavior
Lipid bilayer
Pulmonary Surfactant-Associated Protein B
Chemistry
Peripheral membrane protein
Electric Conductivity
Membrane
Phosphatidylglycerols
Biological membrane
Hydrophobic
Pulmonary Surfactant-Associated Protein C
Solubility
Membrane protein
Biochemistry
Bilayers
Phosphatidylcholines
lipids (amino acids, peptides, and proteins)
Hydrophobic and Hydrophilic Interactions
Subjects
Details
- ISSN :
- 00063495
- Volume :
- 104
- Database :
- OpenAIRE
- Journal :
- Biophysical Journal
- Accession number :
- edsair.doi.dedup.....93d3a1a5623a73e84eddd0fd9202abf9