Interaction of v-Myb oncoprotein with spread chromatin of avian haematopoietic cells

Interactions of v-Myb oncoprotein with spread chromatin of avian LSCC-BM2 c ells expressing v-myb oncogene were studied by means of immunoelectron micr oscopy. The application of this technique using anti-Myb polyclonal antibod y combined with the Miller type spreading for visualisation of chromatin re vealed the presence of Myb protein on stretched chromatin fibres. Intense l abelling was apparent on the chromatin dispersed by hypotonic treatment, wh ere the label was present frequently in clusters, although individual marks along the fibrillar molecules were also found. The combination of hypotoni c and detergent treatment resulted in better dispersal of chromatin, more f requent detection of active transcription units, but also in removal of som e proteins from chromatin fibres. The labelling of chromatin with anti-Myb antibody was substantially reduced in this case and was dependent on deterg ent concentration used. The marker was found less frequently on chromatin f ibres usually present in clusters on remaining protein structures. Our find ings confirmed direct interaction of v-Myb protein with chromatin structure . This interaction is apparently affected by detergent treatment.