IDENTIFICATION OF N-TERMINUS PEPTIDE OF HUMAN GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR AS THE SITE OF NUCLEOTIDE INTERACTION

The interaction of nucleotides with recombinant human granulocyte/macr ophage colony stimulating factor (rhGM-CSF) has been investigated. Uti lizing nucleotide photoaffinity probes [gamma(32)P]-8N(3)ATP and [beta 'P-32]-8N(3)Ap(4)A, an analog of alarmone, the specificity of interact ion was demonstrated by saturation of photoinsertion by these analogs and protection of photoinsertion by these analogs in the presence of n atural nucleotide. The site of photoinsertion was tentatively determin ed to be Ser(9). The photolabeled cytokine has lost most of its biolog ical activity in a cellular proliferation assay, indicating a possible physiological role for this interaction. (C) 1995 Academic Press. Inc .