Purification and partial amino acid sequence of asialo murine granulocyte-macrophage colony stimulating factor

A procedure utilizing reversed-phase high-performance liquid chromatography is described for the purification of asialo granulocyte-macrophage colony stimulating factor (asialo-GM-CSF) from mouse lung-conditioned medium. In the purification, the partially purified factor was treated with neuraminidase to reduce charge heterogeneity due to variable degrees of sialation. Three active forms of the asialo factor were separated by the final reversed-phase liquid chromatography step. These each gave a single major band and several minor bands on polyacrylamide gel electrophoresis and had similar amino acid compositions. The specific activity of purified murine asialo-GM-CSF was approximately 8 X 10(9) colonies per mg of protein. Amino acid sequence determination of the major form gave a single amino-terminal sequence, which has been used to develop oligonucleotide probes for the isolation of two cDNA clones encoding GM-CSF. The nucleotide sequence of these two clones gave a deduced amino acid sequence almost identical with that determined for the amino terminus of asialo-GM-CSF and an amino acid composition very similar to that for asialo-GM-CSF.