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Properties of the M antigen solubilized from genetically high potassium sheep red cells
Abstract:
The M antigen genetically associated with the high potassium (HK) status of sheep red cells was solubilized in 0.5% Triton X-100. This procedure did not impair M-antibody binding in the presence of detergent because solubilized membranes bound M-antibody in units equivalent to control membranes. As judged by M-antibody binding, the antigen was found to be stable in 0.5% Triton X-100 at 4 degree C but lost its activity rapidly at 37 degree C or when diluted to low detergent concentrations. However, the formation of the M antigen-antibody complex prior to dilution or exposure to elevated temperature protected the M antigen from inactivation. Brief exposure to alkaline pH released the extrinsic membrane proteins from red cell membranes without solubilizing the M antigen. The intrinsic membrane proteins were further separated by ion exchange chromatography on Affi-Gel 102. M antigenic activity copurified with the sheep specific protein band 2.2 band 6, and the glycoproteins and appeared to be separate from the main portion of band 3 protein.
Insights
The M antigen, linked to high potassium (HK) red blood cell status in sheep, was successfully solubilized. Antibody binding confirmed its stability under specific conditions, revealing protection mechanisms.
Area of Science:
- Biochemistry
- Immunology
- Membrane Biology
Background:
- The M antigen in sheep red blood cells is genetically associated with high potassium (HK) status.
- Understanding the M antigen's molecular properties is crucial for characterizing red cell membrane proteins.
Purpose of the Study:
- To solubilize the M antigen from sheep red cells.
- To investigate the stability and binding characteristics of the solubilized M antigen.
- To identify proteins associated with M antigenic activity.
Main Methods:
- Solubilization of red cell membranes using 0.5% Triton X-100.
- Assessing M-antibody binding to membranes and solubilized antigen.
- Evaluating antigen stability at different temperatures and detergent concentrations.
- Ion exchange chromatography for protein separation.
Main Results:
- Solubilization in Triton X-100 preserved M-antibody binding.
- The M antigen remained stable at 4°C in detergent but lost activity at 37°C or low detergent concentrations.
- Pre-formation of the M antigen-antibody complex protected the antigen from inactivation.
- M antigenic activity co-purified with specific protein bands (2.2, 6) and glycoproteins, distinct from band 3 protein.
Conclusions:
- The M antigen can be solubilized while retaining its antibody-binding capacity.
- M antigen stability is dependent on detergent concentration and temperature, but complex formation offers protection.
- The M antigen is an intrinsic membrane protein, likely associated with specific glycoproteins and protein bands, separate from band 3.