Myc Family Oncogenes in the Development of Normal and Neoplastic Cells

Abstract

Publisher Summary This chapter reviews the structural and functional features of myc family genes and their products and discusses these properties in relation to known or suspected roles of myc in normal mammalian development and in malignant disease. The most extensive region of homology among c-myc, N-myc, and L-myc gene products is found near the carboxy-terminal portion of various proteins. This region contains two structural motifs identified in transcription and differentiation factors—namely, the leucine zipper and the helix-loop-helix/basic region motifs. These structures are found in a contiguous arrangement, with the leucine zipper located at the carboxy terminus and the helix-loop-helix just amino terminal to the leucine zipper. myc family genes are important in the regulation of normal cellular growth and differentiation. myc family genes exhibit unique expression patterns during mammalian development and the dramatic changes in their expression coincide with critical developmental transitions in many cell lineages. myc family oncoproteins are localized to the nucleus, and they possess significant homology to known sequence-specific transcription factors and for differentiation factors, thereby suggesting that myc-encoded oncoproteins may serve to regulate specific gene expression during growth and differentiation. Although myc family genes share many structural and functional features, their conservation as distinct sequences in evolution indicates important and unique biological activities.