PTPRN and diabetes mellitus: Implication of the mA1AT/HSP complex in the autoimmune process related to diabetes is supported by the significant structural similarity shared by both HSPs, Grp94 in particular, and A1AT with all the peptides/epitopes already identified in the major islet antigen proteins (i.e., INS, GAD65 and IA-2; Figs. 3, 4), a condition not satisfied instead by any of the reference proteins nor by any of the HSPs that show a high degree of structural similarity with Grp94 and HSP70.