The function of ENSG00000155111 (CDK19, cyclin dependent kinase 19) is as follows. Component of the Mediator complex, a transcriptional coactivator required for regulated expression of nearly all RNA polymerase II-dependent genes. Acts as a molecular bridge between gene- specific regulatory proteins and the basal RNA polymerase II transcription machinery. Mediator is recruited to promoters through direct interactions with transcriptional regulators and serves as a scaffold for assembly of the pre-initiation complex with RNA polymerase II and general transcription factors. Contributes to phosphorylation of transcription factors and other substrates, including RNA polymerase II and the Notch1 intracellular domain (ICN1), thereby modulating gene expression programs (PubMed:25344755, PubMed:28855340, PubMed:29440396). Plays a role together with CDK8 in normal macrophage differentiation (By similarity). {ECO:0000250|UniProtKB:Q8BWD8, ECO:0000269|PubMed:25344755, ECO:0000269|PubMed:28855340, ECO:0000269|PubMed:29440396}.