Exonuclease activities associated with DNA polymerases alpha and beta of the archaebacterium Halobacterium halobium.

alpha-like and beta-like DNA polymerases have previously been isolated from a halophilic archaebacterium Halobacterium halobium. In this report, we show that the alpha-like DNA polymerase has an associated 3' to 5'-exonuclease activity which is specific for single-stranded DNA, sensitive to both aphidicolin and N-ethylmaleimide and dependent on high salt concentrations like the polymerase activity. As this DNA polymerase has been shown to contain a primase activity, it may be considered as the equivalent to both eukaryotic DNA polymerases alpha and delta.

Presence of circulating anti-c-myb oncogene product antibodies in human sera.

Bacterially expressed mouse c-myb protein was purified from E. coli extracts and used as antigen to screen human sera for circulating anti-c-myb oncogene product antibodies. Using Western blotting, we have found that human sera contain IgG antibodies to the c-myb gene product.

Reverse transcriptase in archaebacteria. Purification and characterization of a primase-reverse-transcriptase complex from Halobacterium halobium.

A primase-reverse-transcriptase of Halobacterium halobium was purified by column chromatography on DEAE-cellulose, hydroxyapatite and carboxymethyl-cellulose, followed by sedimentation on a glycerol gradient. The enzyme is a multifunctional enzyme containing reverse transcriptase. DNA polymerase and RNase H activities and does not require a performed primer to initiate DNA synthesis.

Circulating antibodies against c-myc oncogene product in sera of colorectal cancer patients.

We developed a Western blot assay using purified human c-myc protein expressed in E. coli in order to look for circulating anti-c-myc antibodies in human sera. The presence of IgG antibodies against c-myc was observed in 25 out of 44 sera from patients with colorectal cancer diagnosed and treated at the Hôpital Curie in Paris, compared to the sera of 46 normal donors of which only 8 samples were positive (p = 0.

Detection of circulating antibodies against c-myc protein in cancer patient sera.

We have partially purified an archaebacterial protein of 84 kD which shares common epitopes with the human c-myc protein as shown by its cross-reactivity with a commercialized anti-human c-myc antiserum. An antiserum raised against the 84 kD protein recognizes a 60 kD protein from HL-60 nuclei. This protein is also recognized by the anti-human c-myc antiserum.