A family of ribonucleoproteins that were originally found as proteins bound to nascent RNA transcripts in the form of ribonucleoprotein particles. Although considered ribonucleoproteins they are primarily classified by their protein component. They are involved in a variety of processes such as packaging of RNA and rna transport within the nucleus. A subset of heterogeneous-nuclear ribonucleoproteins are involved in additional functions such as nucleocytoplasmic transport (active transport, cell nucleus) of RNA and mRNA stability in the cytoplasm.