Calcium is pivotally involved in many biochemical processes in different cell types. This divalent cation mediates its function by interacting with specific calcium binding proteins that serve as calcium sensors and regulatory proteins. In our earlier studies we found that calcium was involved in the protein-protein interaction observed between Ro 60 multiple antigenic peptides (MAPs) and Ro 60 autoantigen. Since calcium was found to bind Ro 60 MAPs we hypothesized that it would renature human recombinant Ro 60 on a protein blot. As hypothesized antibodies to Ro 60 bound significantly higher to the recombinant Ro antigen that was incubated with calcium compared with that incubated without calcium on a polyvinyline fluoride (PVDF) blot. Since the immmunological epitopes of Ro 60 are mainly conformational, we believe that calcium induced a more native tertiary structure in recombinant Ro 60 autoantigen -following blotting to a PVDF membrane.