The RNA- and DNA-binding protein TB-RBP is spatially and developmentally regulated during spermatogenesis.
Testis brain RNA-binding protein (TB-RBP) suppresses translation in vitro and attaches mRNAs to microtubules by binding to conserved elements in the 3' untranslated regions (UTRs) of specific testis and brain mRNAs. Purification of TB-RBP from testicular and brain cytoplasmic extracts has revealed that mouse TB-RBP is 99% identical to the human protein translin, a recombination "hot spot" binding protein associated with chromosomal translocations. Using a cDNA encoding TB-RBP, the gene copy number and the developmental expression of TB-RBP have been analyzed by Southern blotting, Northern blotting, and in situ hybridization. In the mouse, TB-RBP is encoded by a single copy gene. In mouse testes, three TB-RBP mRNAs of about 1.2, 1.7, and 3.0 kb are developmentally regulated with high levels of expression in meiotic and postmeiotic germ cells. A fourth TB-RBP transcript of about 3.2 kb is seen in the brain. In situ hybridization confirms high levels of testicular TB-RBP mRNAs in meiotic and postmeiotic cells, with the highest levels of TB-RBP mRNAs in pachytene spermatocytes and round spermatids of the mouse and in round spermatids of the rat. RNase H digestion assays reveal that the three TB-RBP mRNAs of mouse testes result from processing differences in their 3' untranslated regions. These data demonstrate that multiple TB-RBP mRNAs are primarily expressed in meiotic and postmeiotic germ cells in the mammalian testis, and although the specific RNA-binding ability of TB-RBP appears limited to brain and testis, TB-RBP mRNAs are widely expressed.
Gu
W
W
Department of Biology, Tufts University, Medford, Massachusetts, USA.
Wu
X Q
XQ
Meng
X H
XH
Morales
C
C
el-Alfy
M
M
Hecht
N B
NB
D000818:Animals; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D018628:Gene Dosage; D018507:Gene Expression Regulation, Developmental; D008297:Male; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D016366:Open Reading Frames; D012333:RNA, Messenger; D016601:RNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013091:Spermatogenesis / Q000502:physiology*; D014018:Tissue Distribution
D004268:DNA-Binding Proteins; D008869:Microtubule-Associated Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C490551:STRBP protein, human; C490552:Strbp protein, rat