replicationdependent

Replicationdependent is a term used in molecular biology to describe gene products, RNAs, or cellular processes whose production or function is tied to DNA replication, most often during the S phase of the cell cycle. In eukaryotes, replication-dependent histones are the canonical example. Histone genes encoding core proteins H2A, H2B, H3, and H4 are expressed predominantly during S phase, and their transcripts lack polyadenylation. Instead, their 3' ends form a conserved stem-loop structure that is recognized by the stem-loop binding protein. The synthesis, processing, and turnover of replication-dependent histone mRNAs are tightly coupled to DNA synthesis, so histone production tracks the rate of replication.

Replication-dependent expression contrasts with replication-independent transcription, where some histone variants (for example, H3.3 or H2A.Z) and other chromatin-associated factors can be produced outside S phase and often use polyadenylated mRNAs. In chromatin assembly, replication-dependent histones are deposited onto newly synthesized DNA with the help of chaperone systems such as CAF-1 (chromatin assembly factor 1), which coordinate histone supply with DNA replication.

Beyond histones, the concept applies to other cellular processes whose efficiency or occurrence depends on ongoing DNA replication, or to regulatory programs that are activated specifically during S phase. Misregulation of replication-dependent pathways can impact genome stability and cell-cycle progression, making them a focus in studies of cell biology and cancer.