Catalytic subunit of the DNA primase complex and component of the DNA polymerase alpha complex (also known as the alpha DNA polymerase-primase complex - primosome/replisome) which play an essential role in the initiation of DNA synthesis (By similarity). The primase subunit of the polymerase alpha complex initiates DNA synthesis by oligomerising short RNA primers on both leading and lagging strands (By similarity). ssDNA + n dNTP = ssDNA/pppdN(pdN)n-1 hybrid + (n-1) diphosphate. The presence of the regulatory subunit accelerates the kinetics of initiation and primer extension. Heterodimer of a catalytic subunit and a regulatory subunit, also known as the DNA primase complex. The bound zinc ion is not a cofactor. It is bound to a zinc knuckle motif that may be involved in sequence recognition and the binding of ssDNA (By similarity). Belongs to the eukaryotic-type primase small subunit family.