Alphaprimasekompleksi

Alphaprimasekompleksi, often referred to as the alpha-primase complex, is a multiprotein assembly that serves as the RNA primer–forming component of the eukaryotic DNA replication machinery. It is a key part of the DNA polymerase alpha-primase (Pol α-primase) holoenzyme, coordinating primer synthesis with DNA elongation.

In most eukaryotes, alphaprimasekompleksi consists of two subunits: a primase small subunit (PRIM1) and a primase large subunit (PRIM2). The primase subunits catalyze the synthesis of a short RNA primer, typically about 8–12 nucleotides, at replication origins or on the lagging strand. The RNA primer provides a 3' hydroxyl end for extension by DNA polymerase alpha, which then adds deoxynucleotides to complete the RNA-DNA primer.

Activity is coordinated with the replicative helicase CMG complex (Cdc45–MCM–GINS) and other factors such as replication protein A (RPA) that stabilize the single-stranded template. Regulation occurs through cell-cycle cues and protein interactions that ensure primers are laid down at appropriate times during S phase.

Defects in alphaprimasekompleksi or its interaction with Pol α-primase can lead to replication stress and genome instability, with potential links to developmental disorders and cancer in some organisms.

Understanding alphaprimasekompleksi has implications for studies of genome maintenance and is a common subject of genetic and structural biology research.