Biochemical and subcellular characterization of a squid hnRNPA/B-like protein 2 in osmotic stress activated cells reflects molecular properties conserved in this protein family.

We have identified endogenous p65 to be an SDS-stable dimer protein composed of ~ 37 kDa hnRNPA/B-like subunits. We have investigated molecular properties involved in the stability of dimeric form, and their regulation in the transition between monomeric and dimeric forms of hnRNPA/B-like protein 2. We also investigated a cellular property conserved between squid hnRNPA/B-like protein 2 and human hnRNPA1 protein in a neuronal context. Here we show biochemical properties of a recombinant hnRNPA/B-like protein 2 (rP2) in vitro experiments, as one of p65 subunit. We found that interaction between rP2 and RNA molecules interfered with the dynamics of rP2 dimers formation, involved in disulfide bonds and/or postranslational alterations in distinct stage of SDS-stable dimers formation. In addition, we have performed immunofluorescence in SH-SY5Y cells and observed that the pEGFP-P2 fusion protein was expressed in the nucleus, similar to what is observed for human hnRNPA1 protein. Our results reinforce the idea that p65 is an SDS-stable dimer. Thus, a deeper understanding between monomeric and dimeric transition dynamic is critical into evolution of several neurodegenerative disease.