Binds pre-mRNA and nucleates the assembly of 40S hnRNP particles. 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. Single HNRNPC tetramers bind 230-240 nucleotides. Trimers of HNRNPC tetramers bind 700 nucleotides. 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. 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 (By similarity). Interacts with PPIA/CYPA (By similarity). Component of ribonucleosomes. Phosphorylated on Ser-268 and Ser-306 in resting cells. Sumoylated. Sumoylation reduces affinity for mRNA. Belongs to the RRM HNRPC family. RALY subfamily.