Properties of the myc-Gene Product: Nuclear Association, Inhibition of Transcription and Activation in Stimulated Lymphocytes

Using a variety of myc-specific antibodies against bacterially expressed viral and human cellular myc genes and against synthetic peptides, we have characterized viral and cellular myc-gene products and obtained the following results: (1) Immunofluorescence analysis of MC29-transformed fibroblasts sequentially treated with detergent, nucleases and salt indicates that part of the p11Ogag-myc remains insoluble suggesting its association with the so-called nuclear matrix. (2) Immune-affinity purified p11Ogag-myc protein inhibits transcription of the Adenovirus 2 major late promoter (Ad2 MLP) two- to fourfold if added to in vitro transcription systems. (3) The c-myc gene product expressed in avian lymphoma (RP9) cells was identified as a protein of 55,000 molecular weight, p55c-myc, similar to the avian viral p55v-myc protein of OK10 cells. (4) Myc-specific antibodies gave rise to nuclear fluorescence in HeLa cells and precipitated two proteins of about 62,000 and 49,000 molecular weights which were competed out by the appropriate antigens. (5) Mitogen-stimulated lymphocytes exhibit two novel proteins of similar size detected by myc-specific antibodies.