HNRNPK ( hnRNP K) belongs to the subfamily of ubiquitously expressed heterogeneous nuclear ribonucleoproteins (hnRNPs). The hnRNPs are RNA binding proteins and they complex with heterogeneous nuclear RNA (hnRNA). These proteins are associated with pre-mRNAs in the nucleus and appear to influence pre-mRNA processing and other aspects of mRNA metabolism and transport. While all of the hnRNPs are present in the nucleus, some seem to shuttle between the nucleus and the cytoplasm. The hnRNP proteins have distinct nucleic acid binding properties. The protein encoded by this gene is located in the nucleoplasm where it binds tenaciously to poly(C). This protein is thought to have a role during cell cycle progession. Mutations in HNRNPK lead to Au-Kline / Okamoto syndrome, a genetic condition characterized by heart defects, intellectual disasbility, facial and skeletal abnormalities and delayed language and walking. Deletions in HNRNPK are also associated with myeloid, lymphoid, and hepatocellular cancers. In immunohistochemistry of normal tissue, HNRNPK has nuclear positivity in all tissues throughout the body. References: The UniProt Consortium. Nucleic Acids Res. 47: D506-515 (2019); Nucleic Acids Res. 2016 Jan 4;44(D1):D733-45, PMID:26553804; Cancer Cell. 28 (4): 486–499, PMID: 26412324; "Au-Kline syndrome". Genetics Home Reference, URL: https://ghr.nlm.nih.gov/condition/au-kline-syndrome;