Sequence studies will be continued on HLA antigens using our recently developed procedure for sequencing membrane proteins by radioactive methods. The chemical nature of the genetic variation of histone Hla in corn will be further characterized. Attempts will be made to molecularly clone the corn histone loci under P2/EK1 containment. Work on cloning mammalian immunoglobulin loci will be continued as P3 facilities and an EK2 host/vector system become available. BIBLIOGRAPHIC REFERENCES: Shinnick, T.M., Lund, E., Smithies, O. and Blattner, F.R., Hybridization of Labeled RNA to DNA in Agarose Gels. Nucleic Acid Research (2)10:1911-1929, 1975. Faber, H.E., Kucherlapati, R.S., Poulik, M.D., Ruddle, R.H. and Smithies, O. Beta-2-Microglobulin Locus on Human Chromosome 15. Somatic Cell Genetics 2: 141-153, 1976.