DNA polymerase-associated lectin (DPAL) and its binding to the galactose-containing glycoconjugate of the replication complex

Biosci Rep. 1999 Oct;19(5):433-47. doi: 10.1023/a:1020268407342.


The highly purified DNA Pol-alpha from rat prostate tumor (PA-3) and human neuroblastoma (IMR-32) cells appeared to be inhibited by Ricin (RCA-II), and Con-A. Loss of activity (40 to 60%) of a specific form of DNA polymerase from IMR-32 was observed when the cells were treated with tunicamycin [Bhattacharya, P. and Basu, S. (1982) Proc. Natl. Acad. Sci., USA 79:1488-1492]. Binding of ConA and RCA to human recombinant DNA polymerase-alpha showed a specific labile site in the N-terminus [Hsi et al.. (1990) Nucleic Acid Res. 18:6231-6237]. The catalytic polypeptide, DNA polymerase-alpha of eukaryotic origin, was isolated from developing tissues or cultured cells as a family of 180 to 120 kDa polypeptides, perhaps derived from a single primary structure. Immunoblot analysis with a monoclonal antibody (SJK-237-71) indicated that the lower molecular weight polypeptides resulted from either proteolytic cleavage of post-translational modification after specific cleavages. Present results suggest DNA polymerase-alpha from embryonic chicken brain (ECB) contains an alpha-galactose-binding subunit which may be involved in developmental regulation of the enzyme. It was shown before that the catalytic subunit of DNA polymerase-alpha reduces from 186 kDa in 11-day-old ECB to 120 kDa in 19-day-old ECB [Ray, S. et al. Cell Growth and Differentiation 2:567-573] by the treatment with methyl-alpha-galactose. The low molecular weight DNA polymerase activity (120 kDa) can be reconstituted to high molecular weight (Mr = 186 kDa) with an alpha-galactose binding, 56kDa lectin-like protein. Polyclonal antibodies raised against the purified lectin were able to precipitate DNA. Pol-alpha as determined by immunostaining with the polymerase-alpha-specific monoclonal antibody SJK 132-20, suggesting this is a DNA polymerase associated-lectin (DPAL). RCA-II and GS-I-Sepharose 4B chromatographies resulted in significant purification of DNA-alpha and a complete separation of polymerase complex and primase.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Catalytic Domain
  • Chick Embryo
  • Chromatography, High Pressure Liquid
  • Concanavalin A / chemistry
  • DNA Polymerase I / chemistry*
  • DNA Primase / chemistry
  • DNA Replication
  • Galactose / chemistry*
  • Glycoconjugates / chemistry*
  • Humans
  • Lectins / chemistry*
  • Methylgalactosides / chemistry
  • Molecular Weight
  • Precipitin Tests
  • Protein Binding
  • Rats
  • Toxins, Biological / chemistry
  • Tumor Cells, Cultured


  • Glycoconjugates
  • Lectins
  • Methylgalactosides
  • RCA II
  • Toxins, Biological
  • Concanavalin A
  • methyl beta-galactoside
  • DNA Primase
  • DNA Polymerase I
  • Galactose