HnRNPs H, H′ and F behave differently with respect to posttranslational cleavage and subcellular localization

Abstract

hnRNPs H, H′ and F belong to a subfamily of the hnRNPs sharing a high degree of sequence identity. Eukaryotic expression and specific C-terminal antibodies were used to demonstrate great variation in the intracellular fate of the proteins. hnRNPs H and H′ become posttranslational cleaved into C-terminal 35 kDa proteins (H C, H′ C) and possibly into N-terminal 22 kDa proteins. No detectable cleavage was observed for hnRNP F. hnRNP H/H′ is almost exclusively localized to the nucleus of many cell types while hnRNP F varies from a predominant nuclear localization in some cells to a predominant cytoplasmic localization in other cells. The different fates may reflect differences in functional roles that so far only have included nuclear functions. The presence of significant quantities of hnRNP F in the cytoplasm of many cells indicates that it also may have a functional role here.