Calcium Binding by Ro 60 Multiple Antigenic Peptides on PVDF Membrane
Biji T Kurien1, Michael P Bachmann
1Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA, biji-kurien@omrf.org.
Methods in Molecular Biology (Clifton, N.J.)
|July 4, 2015
Summary
Systemic lupus erythematosus autoantibodies target Ro RNP particles. This study demonstrates that the Ro 60 antigen is a calcium-binding protein, crucial for its interactions within the RNP complex.
Area of Science:
- Immunology
- Molecular Biology
- Biochemistry
Background:
- Autoantibodies against ribonucleoprotein (RNP) particles, like Ro RNP, are characteristic of systemic lupus erythematosus.
- The Ro RNP particle includes the 60 kDa Ro protein (Ro 60 or SS-A) associated with hY RNAs.
- Previous work indicated calcium's role in protein-protein interactions within the Ro 60 RNP particle.
Purpose of the Study:
- To investigate the hypothesis that the 60 kDa Ro autoantigen is a calcium-binding protein.
- To elucidate the role of calcium in the structural and functional properties of the Ro 60 RNP particle.
Main Methods:
- Electrophoresis of 60 kDa Ro multiple antigenic peptides (MAPs) and transfer to PVDF membrane.
- Calcium binding assays using the Quin-2 system.
- Comparison of calcium binding with bovine serum albumin and a Sm autoantigen MAP.
Main Results:
- Several Ro 60 MAPs demonstrated calcium binding.
- Bovine serum albumin, a known calcium-binding protein, also showed calcium binding.
- A MAP derived from the Sm autoantigen did not bind calcium.
Conclusions:
- The Ro 60 antigen exhibits calcium-binding properties.
- Calcium binding is implicated in the protein-protein interactions involving the Ro 60 antigen.
- These findings support the proposal that Ro 60 is a calcium-binding protein.
