Autoantibody to gravin is expressed more strongly in younger and nonthymomatous patients with myasthenia gravis

Abstract

Gravin is expressed in several cell and tissue types as either 300 kDa doublet or 250 kDa proteolytic products. It is a cytoplasmic antigen that reacts with the serum of patients with myasthenia gravis (MG). Autoantibodies to gravin residues 1477-1781 are highly specific for MG. In the present study, we examined residues 1477-1781 in detail and found that residues 1542-1547 of gravin protein, which had sequence homology with the binding sequences of two protein A-kinase anchoring proteins, were highly reactive to MG serum. Antigravin antibody activities were stronger in younger and nonthymomatous patients. These findings suggest that antigravin antibody activities could be a useful prognostic factor and that the gravin antibody of MG may have a function which prevents the protein A-kinase binding pathway.