Enables RNA polymerase II C-terminal domain binding activity; nucleic acid binding activity; and promoter-specific chromatin binding activity. Involved in several processes, including RNA localization to chromatin; cellular response to leukemia inhibitory factor; and regulation of gene expression. Acts upstream of or within with a positive effect on mRNA metabolic process. Acts upstream of or within cardiac muscle cell development. Located in inactive sex chromosome and nucleus. Part of ribonucleoprotein complex. Is expressed in several structures, including branchial arch; future brain; limb primordium; tail bud; and unsegmented mesenchyme. Human ortholog(s) of this gene implicated in developmental and epileptic encephalopathy 54. Orthologous to human HNRNPU (heterogeneous nuclear ribonucleoprotein U). [provided by Alliance of Genome Resources, Apr 2022]