Conspicuous accumulation of transcription elongation repressor hrp130/CA150 on the intron-rich Balbiani ring 3 gene.
Chromosomal puffs on the polytene chromosomes in the dipteran Chironomus tentans offer the possibility of comparing the appearance of RNA-binding proteins at different transcription sites. We raised a monoclonal antibody that recognized a 130 kDa protein, designated hrp130. Immunocytological analysis of isolated chromosomes showed that hrp130 is heavily accumulated in a specific puff, called Balbiani ring 3; only occasionally is hrp130 abundant in one or two additional puffs on other chromosomes. The immunolabeling was sensitive to RNase treatment, suggesting that hrp130 is associated with nascent ribonucleoproteins. As shown by immunoelectron microscopy hrp130 is distributed along the active BR3 genes. The full sequence of hrp130 was determined by cDNA cloning. The protein comprises 1028 amino acids and contains three WW domains in the N-terminal half and six FF domains in the C-terminal half of the molecule. The protein is conserved from Caenorhabditis elegans to mammals; the human homolog is known as the transcription elongation repressor CA150. We propose that the abundance of hrp130/CA150 in BR3 is connected with the exceptionally high level of splicing in this locus and that hrp130/CA150 adjusts the transcription rate to the numerous splicing events taking place along the gene to ensure proper splicing.
Sun
Xin
X
Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institutet, 17177 Stockholm, Sweden.
Zhao
Jian
J
Kylberg
Karin
K
Soop
Teresa
T
Palka
Kevin
K
Sonnhammer
Erik
E
Visa
Neus
N
Alzhanova-Ericsson
Alla T
AT
Daneholt
Bertil
B
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D002683:Chironomidae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D002875:Chromosomes / Q000378:metabolism / Q000648:ultrastructure*; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004277:DNA, Single-Stranded; D005786:Gene Expression Regulation; D007114:Immunization; D019476:Insect Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D007438:Introns / Q000235:genetics*; D007814:Larva / Q000254:growth & development / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D016601:RNA-Binding Proteins / Q000276:immunology / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000276:immunology / Q000378:metabolism; D012469:Salivary Glands / Q000378:metabolism / Q000648:ultrastructure; D012471:Salivary Proteins and Peptides / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D016415:Sequence Alignment; D015534:Trans-Activators / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D014158:Transcription, Genetic; D035602:Transcriptional Elongation Factors
D000911:Antibodies, Monoclonal; C112569:BR3 protein, Chironomus tentans; D018076:DNA, Complementary; D004277:DNA, Single-Stranded; D019476:Insect Proteins; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; D012261:Ribonucleoproteins; D012471:Salivary Proteins and Peptides; C108440:TCERG1 protein, human; C473940:Tcerg1 protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors; D035602:Transcriptional Elongation Factors