Atomic Force Microscopy of Asymmetric Membranes from Turtle Erythrocytes

Abstract

The cell membrane provides critical cellular functions that rely on its elaborate structure and organization. The structure of turtle membranes is an important part of an ongoing study of erythrocyte membranes. Using a combination of atomic force microscopy and single-molecule force spectroscopy, we characterized the turtle erythrocyte membrane structure with molecular resolution in a quasi-native state. High-resolution images both leaflets of turtle erythrocyte membranes revealed a smooth outer membrane leaflet and a protein covered inner membrane leaflet. This asymmetry was verified by single-molecule force spectroscopy, which detects numerous exposed amino groups of membrane proteins in the inner membrane leaflet but much fewer in the outer leaflet. The asymmetric membrane structure of turtle erythrocytes is consistent with the semi-mosaic model of human, chicken and fish erythrocyte membrane structure, making the semi-mosaic model more widely applicable. From the perspective of biological evolution, this result may support the universality of the semi-mosaic model.

Topological Structures and Membrane Nanostructures of Erythrocytes after Splenectomy in Hereditary Spherocytosis Patients via Atomic Force Microscopy

“…The unique combination of high-resolution topography and operation under physiological environments has made it useful in many studies of cell properties [14, 15]. Though AFM has been employed to image RBCs in lab for over a decade [16, 17].…”

“…In past several decades, AFM has become a powerful technique for studying the mechanical properties (stiffness, viscoelasticity, hardness, and adhesion) of various biological materials. The unique combination of high-resolution topography and operation under physiological environments has made it useful in many studies of cell properties [ 14 , 15 ]. Though AFM has been employed to image RBCs in lab for over a decade [ 16 , 17 ].…”

Enantiomeric Effect of d-Amino Acid Substitution on the Mechanism of Action of α-Helical Membrane-Active Peptides

“…The RP-HPLC retention time has been widely used to represent the relative hydrophobicity of peptides in many studies [ 11 , 13 , 18 , 19 ].The relative hydrophobicity of the peptides was determined by the RP-HPLC retention times at 25 °C. The change in hydrophobicity of the peptides caused by d -amino acid substitutions was mainly due to the disruption of the helical structure.…”

“…The E. coli and peptide-treated bacteria samples (after treatment for 30 min) were applied onto mica and imaged in air using the contact mode and recorded with 512 × 512 pixels. The images of HeLa cells and peptide-treated HeLa cells (after treatment for 5 min) were obtained in Dulbecco’s Modified Eagle’s medium (DMEM) using the Acoustic AC (AAC) mode and recorded with 512 × 512 pixels [ 19 ]. Alternatively, the adsorbed HeLa cells were fixed with 4% paraformaldehyde for 30 min before imaging with AFM.…”

Structural and functional studies of erythrocyte membrane-skeleton by single-cell and single-molecule techniques

“…Based on SMFS, Wang et al observed the membrane proteins of erythrocyte and proposed a novel semi-mosaic model for the erythrocyte membrane organization. [87][88][89] Although application of SMFS sheds new light on the studies of erythrocyte membrane proteins, the anatomy of erythrocyte membrane-skeleton at single-molecule level by AFM still lack a satisfactory level of understanding up to date.…”