Binds pre-mRNA and nucleates the assembly of 40S hnRNP particles (PubMed:8264621). Interacts with poly-U tracts in the 3'-UTR or 5'-UTR of mRNA and modulates the stability and the level of translation of bound mRNA molecules (PubMed:12509468, PubMed:16010978, PubMed:7567451, PubMed:8264621). Single HNRNPC tetramers bind 230-240 nucleotides. Trimers of HNRNPC tetramers bind 700 nucleotides (PubMed:8264621). May play a role in the early steps of spliceosome assembly and pre-mRNA splicing. N6-methyladenosine (m6A) has been shown to alter the local structure in mRNAs and long non-coding RNAs (lncRNAs) via a mechanism named 'm(6)A-switch', facilitating binding of HNRNPC, leading to regulation of mRNA splicing (PubMed:25719671). Tetramer composed of 3 copies of isoform C1 and 1 copy of isoform C2. Assembly of 3 tetramers with bound pre-mRNA gives rise to a 19S complex that interacts with HNRNPA2B1 tetramers. Component of the 40S hnRNP particle. Identified in the spliceosome C complex. Interacts with IGF2BP1. Interacts with DHX9; this interaction is direct, enhanced probably by their concomitant binding to RNA and mediates the attachment to actin filaments (PubMed:11687588). Interacts with PPIA/CYPA (PubMed:25678563). Component of ribonucleosomes. Phosphorylated on Ser-260 and Ser-299 in resting cells. Phosphorylated on Ser-253 and on 1 serine residue in the poly-Ser stretch at position 238 in response to hydrogen peroxide. Sumoylated. Sumoylation reduces affinity for mRNA. Belongs to the RRM HNRPC family. RALY subfamily. Extended N-terminus.