The cellular abl proto-oncogene encodes a proteintyrosine kinase and is expressed in many cell types in two or three mRNA size species. Four types of mouse c-abl cDNAs have been cloned from 70Z/3 lymphoid cells that have different 5′ sequences encoding predicted N-terminal regions of 20-45 amino acids. One of the four cDNAs has a predicted N-terminal sequence of met-gly-gln in common with the gag N terminus of v-abl. The 5′ heterogeneity appears to be generated by alternative addition of 5′ exons onto a common set of 3′ exons. Alternative splicing occurs at the same site at which bcr sequences join to abl sequences in the Philadelphia chromosome translocation.
Bibliographical noteFunding Information:
We thank Drs. Samuel Speck and Michael Mueckler for their help in the cDNA cloning, Richard Mann for his help in the GenBank search, and Ginger Pierce for typing the manuscript. This work was supported by Program Project Grant CA 38497from the National Cancer Institute. Y. B.-N. was supported by a Fogarty International postdoctoral fellowship. A. B. is supported by The Netherlands Organization for the Advancement of Pure Research (ZWO).