Nuclear compartmentalization of the v-myb oncogene product

Nuclei obtained from chicken leukemic myeloblasts transformed by avian myeloblastosis virus were fractionated into various subnuclear compartments, which were then analyzed by specific immunoprecipitation for the presence of the leukemogenic product, p48v-myb, of the viral oncogene. In cells labeled for 30 or 60 min with L-[35S]methionine and in unlabeled exponentially dividing leukemic cells analyzed by Western blotting, p48v-myb was detected within the nucleoplasm (29 +/- 9% [standard deviation] of the total), chromatin (7 +/- 4%), and lamina-nuclear matrix (64 +/- 9%). Also, in myeloblasts analyzed by immunofluorescence during mitosis, p48v-myb appeared to be dispersed through the cell like the lamina-nuclear matrix complex. Strong attachment to the nuclear matrix-lamina complex suggests that p48v-myb may be involved in DNA replication or transcription or both.