Primasepol

Primasepol is a hypothetical multifunctional enzyme proposed to combine RNA primer synthesis with DNA extension during DNA replication. The name blends primase and polymerase, reflecting the suggested dual activities in a single polypeptide.

In speculative models, primasepol would contain a primase-like domain that initiates RNA primers de novo and a DNA polymerase domain that immediately extends the primer with DNA. A flexible linker between domains would allow rapid hand-off and coordinated primer synthesis and elongation.

Predicted properties include two catalytic sites, dependence on divalent metal ions, and regulatory elements enabling activity under replication stress. Some in silico analyses have identified multi-domain proteins bearing both primase-like and polymerase-like motifs; however, these findings remain unconfirmed as functional primasepol enzymes.

Relation to known systems: Primasepol would differ from the bacterial primase–helicase and the eukaryotic Pol alpha–primase complexes by offering a single, integrated enzyme for primer creation and short DNA synthesis. Its existence would expand views on replication initiation diversity.

Status: There is no experimental evidence for an active primasepol enzyme. It remains a term used in theoretical discussions and speculative models. If discovered, detailed biochemical and structural characterization would determine how such a protein operates within cellular replication pathways.