Triton shells of intact erythrocytes

Area of Science:

• Cell Biology
• Biochemistry
• Membrane Protein Analysis

Background:

• Approximately 40% of human erythrocyte membrane proteins resist solubilization by Triton X-114.
• These resistant proteins form a Triton shell, maintaining the erythrocyte's size and shape, indicative of a cytoskeleton.

Purpose of the Study:

• To characterize the protein and lipid composition of the Triton shell.
• To investigate the structural components of the erythrocyte cytoskeleton.

Main Methods:

• Solubilization of erythrocyte membranes with varying Triton X-114 concentrations.
• Analysis of protein and lipid content in the resulting Triton shells.
• Electrophoresis and protease treatment for protein identification.
• Electron microscopy of Triton shells.

Main Results:

• Lipid content decreased with increasing Triton concentration, while most proteins remained constant.
• Spectrin, actin, and specific components (bands 3', 7) were identified in the Triton-insoluble complex.
• Electron microscopy revealed beaded filaments (80-120 Å diameter) within the Triton shells, primarily composed of spectrin.

Conclusions:

• The Triton shell represents a stable erythrocyte cytoskeleton.
• Spectrin is a major component of the filamentous structures within the cytoskeleton.
• Triton shells are a promising source for investigating the erythrocyte cytoskeleton.