Alternative titles; symbols
HGNC Approved Gene Symbol: PRIM2
Cytogenetic location: 6p11.2 Genomic coordinates (GRCh38): 6:57,221,540-57,646,850 (from NCBI)
DNA replication in human cells is initiated by a complex apparatus containing a DNA polymerase-alpha/primase complex that is well conserved from yeast to human. The DNA polymerase-alpha/primase complex contains 4 subunits: the polymerase-alpha p180 (POLA; 312040) and p68 (POLA2) subunits, and the primase p58 (PRIM2A) and p49 (PRIM1; 176635) subunits. Primase synthesizes oligoribonucleotides that serve as primers for the initiation of DNA synthesis. It plays a role in both the initiation of DNA replication and the synthesis of Okazaki fragments for lagging strand synthesis (Shiratori et al., 1995).
By RT-PCR of embryonic kidney cell line RNA using degenerate primers based on mouse and yeast primase subunits, followed by 5-prime RACE, Stadlbauer et al. (1994) cloned the primase p58 subunit. The deduced 446-amino acid protein shares 89% identity with mouse p58, with 5 regions of homology distributed over the central part of the protein. The N and C termini are less well conserved.
Stadlbauer et al. (1994) demonstrated that mouse and human p58 showed no primase activity in the absence of p48.
Zerbe and Kuchta (2002) found that deletion of met288 to leu313 within the polymerase-beta (174760)-like domain of human p58 resulted in a protein that bound to the primase p49 subunit but was unable to support primer synthesis on any template when assays contained only Mg(2+). Including Mn(2+), a metal that stimulates initiation of primer synthesis, allowed the p49/p58 primase complex to synthesize primers at a rate only moderately lower than that of the wildtype enzyme on templates consisting only of deoxycytidylates. By point mutagenesis, Zerbe and Kuchta (2002) determined that arg302, arg306, and lys314 were required for both primer initiation and translocation. Conversion of these residues to alanine interfered with initiation and significantly decreased the processivity of primase. Zerbe and Kuchta (2002) concluded that the polymerase-beta-like region of p58 is important for primer initiation, translocation, and counting.
By PCR amplification using DNAs from a panel of somatic cell hybrids, Shiratori et al. (1995) mapped the PRIM1 gene and the PRIM2 gene to chromosomes 1 and 6, respectively. By fluorescence in situ hybridization using several genomic DNA probes, they mapped the PRIM1 gene to 1q44 and two PRIM2 loci (PRIM2A and PRIM2B) to 6p12-p11.1. In an erratum to Shiratori et al. (1995), the authors stated that the gene on 1q44 was in fact a processed PRIM1 pseudogene (PRIM1P). The PRIM2B locus identified by Shiratori et al. (1995) may also be a pseudogene (Scott, 2004).
Scott, A. F. Personal Communication. Baltimore, Md. 9/8/2004.
Shiratori, A., Okumura, K., Nogami, M., Taguchi, H., Onozaki, T., Inoue, T., Ando, T., Shibata, T., Izumi, M., Miyazawa, H., Hanaoka, F., Murakami, Y., Eki, T. Assignment of the 49-kDa (PRIM1) and 58-kDa (PRIM2A and PRIM2B) subunit genes of the human DNA primase to chromosome bands 1q44 and 6p11.1-p12. Genomics 28: 350-353, 1995. Note: Erratum: Genomics 44: 251 only, 1997. [PubMed: 8530050] [Full Text: https://doi.org/10.1006/geno.1995.1155]
Stadlbauer, F., Brueckner, A., Rehfuess, C., Eckerskorn, C., Lottspeich, F., Forster, V., Tseng, B. Y., Nasheuer, H.-P. DNA replication in vitro by recombinant DNA-polymerase-alpha-primase. Europ. J. Biochem. 222: 781-793, 1994. [PubMed: 8026492] [Full Text: https://doi.org/10.1111/j.1432-1033.1994.tb18925.x]
Zerbe, L. K., Kuchta, R. D. The p58 subunit of human DNA primase is important for primer initiation, elongation, and counting. Biochemistry 41: 4891-4900, 2002. [PubMed: 11939784] [Full Text: https://doi.org/10.1021/bi016030b]