Characterization of hnRNP A2 and B1 using monoclonal antibodies: intracellular distribution and metabolism through cell cycle.

Heterogeneous nuclear ribonucleoprotein (hnRNP) A2/B1 are nuclear RNA binding proteins involved in pre-RNA processing. The alternative splicing of the second mini exon of A2/B1 gene produces A2 and less abundant B1. It has been reported that patients with autoimmune diseases frequently have blood autoantibody valence for A2/B1, and recently that the overexpression, especially of B1, is useful for detecting cancers in early stage. Three anti-A2/B1 monoclonal antibodies were developed using recombinant A2 protein and synthesized peptides around the second splicing site. Three antibodies could separately recognize A2 and B1, and their specificity made them useful in the study of the biochemical and functional properties of A2 and B1. These antibodies have demonstrated differences between A2 and B1 in the intracellular distribution and in the metabolism through cell cycle. They are valuable reagents to clarify the clinical significance of A2/B1 in autoimmune diseases and cancers.