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). During the S phase of the cell cycle, the DNA polymerase alpha complex (composed of a catalytic subunit pol1, an accessory subunit spb70/pol12 and two primase subunits, the catalytic subunit spp1/pri1 and the regulatory subunit spp2/pri2) is recruited to DNA at the replicative forks (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 NTP = ssDNA/pppN(pN)n-1 hybrid + (n-1) diphosphate. Heterodimer of a catalytic subunit spp1/pri1 and a regulatory subunit spp2/pri2, also known as the DNA primase complex (By similarity). Component of the alpha DNA polymerase complex (also known as the alpha DNA polymerase-primase complex) consisting of four subunits: the catalytic subunit pol1, the accessory subunit spb70/pol12, and the primase complex subunits spp1/pri1 and spp2/pri2 respectively (PubMed:15314153, PubMed:11027257, PubMed:11160827). Constitutively expressed throughout the cell cycle (at protein level). 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.