A RNA helix-destabilizing protein is a major component of Artemia salina nuclear ribonucleoproteins.

Abstract
A major component of 30S heterogeneous nuclear ribonucleoprotin (hnRNP) particles from A. salina is HD40, a protein that has been characterized as a RNA helix-destabilizing protein. HD40 binds to and disrupts the secondary structure of nuclear RNA fragments isolated from 30S hnRNP with a stoichiometry of 1 protein per 10-12 nucleotides. The addition of HD40 in excess of this ratio results in the formation of bead-like HD40-nuclear RNA complexes that are similar in properties and appearance to native 30S hnRNP particles. The heterogeneous nuclear RNA (hnRNA) in the HD40-hnRNA complexes is unstacked and unfolded to about the same extent as the RNA in the native 30S hnRNP particles, HD40 is strikingly similar in MW (40,000) and amino acid composition (no cysteine, high glycine, presence of dimethylarginine and blocked NH2 terminus) to eukaryotic hnRNP proteins isolated from many cell types. HD40 can be separated into 3 isoelectric species with basic pIs, which appear to be posttranslational modifications of a single polypeptide chain.