Gunter Steiner, Zdeno Cervenak, Karl Skriner, Erhan Suleymanoglu.
Molecular Cloning, Expression and Immunochemical properties of new Human hnRNP A/B type auto antigen.
Biomedica Jan ;19:8-17.

Heterogeneous nuclear ribonucleoproteins (hnRNPs) represent a group of evolutionarily conserved RNA - protein assemblies, highly encountered in the cell nucleus of human cells. These particles have been considered promising for prognosing and monitoring of systemic autoimmune diseases. Anti-hnRNP autoantibodies are reported in patients suffering from different rheumatic dieseases since 1980s. The strong correlation between particular autoimmune target and the type of disorder is well established. However, the searched highly specific autoantibody serving as diagnostic pathological indicator is not yet described. In this context, these ribonucleoproteins are valuable tools for employment as disease specific markers. Screening of cDNA expression and immunochemical features of previously unknown hnRNP AIB type particle are described here, emphasizing its clinical significance in terms of disease specificity and sensitivity. It is a member of a 2xRNA-binding domain (RBD)-glycine family of heterogeneous nuclear ribonucleoproteins. A cDNA was isolated from a human liver library encoding a 296 amino acid human hnRNP A3 polypeptide, highly homologous to the fetal brain cDNA, as well as to hnRNP A1 and A2. The highest degree of similarity is shared with a cDNA from Xenopus laevis. Bacterial expression of the liver cDNA produced a 32 kDa protein, whose authoreactivity was investigated by Western blotting, employing more than 300 sera from rheumatic patients. Immunochemical analysis supported the evidence that a novel member of human hnRNP AIB group of proteins have been cloned, which potentially play a role as an autoantigen in human systemic autoimmunity.

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