PU.1 is a component of a multiprotein complex which binds an essential site in the murine immunoglobulin lambda 2-4 enhancer.
B-cell-specific enhancers have been identified in the immunoglobulin lambda locus 3' of each constant-region cluster. These enhancers contain two distinct domains, lambda A and lambda B, which are essential for enhancer function. lambda B contains a near-consensus binding site for the Ets family of transcription factors. In this study, we have identified a B-cell-specific protein complex which binds the lambda B motif of the lambda 2-4 enhancer in vitro and appears necessary for the activity of the enhancer in vivo, since mutations in lambda B which prevent this interaction also eliminate enhancer function. This complex contains PU.1, a member of the Ets family, and a transcriptional activator whose expression is restricted to cells of the hematopoietic system with the exception of T lymphocytes. In addition, it contains a factor which binds specifically to a region adjacent to the PU.1 binding site. This factor cannot bind lambda B autonomously but appears to require interaction with the PU.1 protein to stabilize its association with the DNA. This complex may be identical or related to the PU.1/NF-EM5 complex which interacts with a homologous DNA element in the immunoglobulin kappa 3' enhancer.
Eisenbeis
C F
CF
Department of Molecular Genetics and Cell Biology, University of Chicago, Illinois 60637.
Singh
H
H
Storb
U
U
D000818:Animals; D001483:Base Sequence; D001667:Binding, Competitive; D004247:DNA; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D007146:Immunoglobulin lambda-Chains / Q000235:genetics*; D046911:Macromolecular Substances; D008745:Methylation; D051379:Mice; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D050783:Proto-Oncogene Proteins c-ets; D015682:Retroviridae Proteins, Oncogenic; D014157:Transcription Factors
D004268:DNA-Binding Proteins; D007146:Immunoglobulin lambda-Chains; D046911:Macromolecular Substances; D046912:Multiprotein Complexes; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D015682:Retroviridae Proteins, Oncogenic; D014157:Transcription Factors; C062022:v-Spi-1 protein, Friend spleen focus-forming virus; D004247:DNA