RAG-1 Interacts with the Repeated Amino Acid Motif of the Human Homologue of the Yeast Protein SRP1
Genes for immunoglobulins and T-cell receptor are generated by a process known as V(D)J recombination. This process is highly regulated and mediated by the recombination activating proteins RAG-1 and RAG-2. By the use of the two-hybrid protein interaction system, we isolated a human protein that specifically interacts with RAG-1. This protein is the human homologue of the yeast SRP1 (suppressor of a temperature-sensitive RNA polymerase I mutation). The SRP1-1 mutation is an allele-specific dominant suppressor of a temperature-sensitive mutation in the zinc binding domain of the 190-kDa subunit of Saccharomyces cerevisiae RNA polymerase I. The human SRP cDNA clone was used to screen a mouse cDNA library. We obtained a 3.9-kbp cDNA clone encoding the mouse SRP1. The open reading frame of this cDNA encodes a 538-amino acid protein with eight degenerate repeats of 40-45 amino acids each. The mouse and human SRP1 are 98% identical, while the mouse and yeast SRP1 have 48% identity. After cotransfection of the genes encoding RAG-1 and human SRP1 into 293T cells, a stable complex was evident. Deletion analysis indicated that the region of the SRP1 protein interacting with RAG-1 involved four repeats. The domain of RAG-1 that associates with SRP1 mapped N-terminal to the zinc finger domain. Because this region of RAG-1 is not required for recombination and SRP1 appears to be bound to the nuclear envelope, we suggest that this interaction helps to localize RAG-1.
© 1994 by National Academy of Sciences. Contributed by David Baltimore, April 14, 1994. We thank Pamela Svec for her excellent technical assistance; E. Spanopoulou, H. L. Liou, and B. Meyer for antibodies and plasmids; Dr. Michel C. Nussenzweig for critical review of this manuscript; and J. Carcamo, J.C. Vera, and B. Chen for many helpful comments on the manuscript. P.C. was supported by a postdoctoral fellowship from the Irvington Institute for Medical Research. Z.-S.Y. was supported by a fellowship from the Leukemia Society of America. This work was supported by National Institutes of Health Grant CA54162 to D.B. The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. 11734 solely to indicate this fact.
Published - CORpnas94.pdf