part of alpha DNA polymerase:primase complex A complex of four polypeptides, comprising large and small DNA polymerase alpha subunits and two primase subunits, which are capable of catalyzing the synthesis of an RNA primer on the lagging strand of replicating DNA and the subsequent synthesis of a small stretch of DNA. The smaller of the two primase subunits alone can catalyze oligoribonucleotide synthesis. DNA polymerase alpha:primase complex primosome pol-prim heterotetrameric polymerase alpha holoenzyme GO:0005658 cellular_component DNA polymerase complex nuclear replisome nuclear DNA-directed RNA polymerase complex