Dr. Steitz's laboratory has identified this activity in 
crude extracts of HeLa cells. When the extracts are 
incubated with MgCl^, dATP, TTP, dGTP, and the syn- 
thetic oligonucleotide (TTAGGG)^ (representing 
the human telomere sequence), DNA products that 
form a 6 nucleotide repeating pattern are observed. 
Oligonucleotides containing nontelomeric se- 
quences are not primers for the reaction, w^hereas 
oligonucleotides representing telomeres of other 
organisms can replace the (TTAGGG)^ primer, giv- 
ing synthesis of the identical TTAGGG repeat se- 
quence. Telomerase activity is sensitive to ribo- 
nuclease A, micrococcal nuclease, and proteinase K, 
indicating the enzyme is probably a ribo- 
nucleoprotein. A search for the telomerase RNA 
component is currently under way. This is the first 
demonstration of telomerase activity in higher eu- 
karyotes and establishes the generality of telomer- 
ase-mediated telomere replication. 
IV Transcription and Function of Epstein-Barr Virus 
Small RNAs. 
Lymphocytes infected with Epstein-Barr virus 
(EBV) produce two virus-encoded small nuclear 
RNAs, EBER 1 and 2. Their high abundance (up to 
10^/cell) in latency suggests that EBERs are involved 
in EBV-directed cell immortalization, but their exact 
function is not known. Small RNAs similar to EBERs 
PUBLICATIONS 
exist in cells infected with EBV-like viruses of ba- 
boons and chimpanzees. 
Previously, Dr. Steitz's laboratory discovered that 
EBER genes are unique in having active promoter 
elements that resemble those typical of both class II 
and class III genes. In addition to internal control 
regions, they have upstream sites that bind the Spl 
transcription factor and activating transcription fac- 
tor (ATP) , as well as a TATA box. Presently the labo- 
ratory is asking how RNA polymerase II is pre- 
vented from transcribing the EBER genes, focusing 
attention on the TATA box. Whether the EBERs are 
transactivated by a virally encoded protein or in- 
duced by cAMP, which is known to function 
through the ATP site, is also being investigated. 
Studies of EBER function have begun with an 
analysis of associated proteins. The only protein 
known to bind EBERs is the La autoantigen, a 50 
kDa phosphoprotein that associates at least tran- 
siently with the 3' ends of all RNA polymerase III 
transcripts and has been implicated in transcription 
termination. Recently a second novel protein has 
been identified and is being cloned. Its character- 
ization should help elucidate the role of EBER in 
the transformed lymphocyte. 
Dr. Steitz is also Professor of Molecular Biophys- 
ics and Biochemistry at Yale University School of 
Medicine. 
Articles 
Black, D.L., and Pinto, A.L. 1989. U5 small nuclear ribonucleoprotein: RNA structure analysis and ATP-depen- 
dent interaction with U4/U6. Mol Cell Biol 
Bond, U. 1988. Heat shock but not other stress inducers leads to the disruption of a sub-set of snRNPs and 
inhibition of in vitro splicing in HeLa cells. EMBO /7:3509-3518. 
Bruzik, J.P, Van Doren, K., Hirsh, D., and Steitz, J.A. 1988. Trans splicing involves a novel form of small nu- 
clear ribonucleoprotein particles. Nature 335:559-562. 
Crouch, D., and Liebke, H. 1989. The molecular cloning of a mouse Ro RNA, myl-like sequence. Nucleic 
Acids Res 17:4890. 
Gottlieb, E., and Steitz, J.A. 1989. The RNA binding protein La influences both the accuracy and the efficiency 
of RNA polymerase III transcription in vitro. £/WBO/ 8:841-850. 
Gottlieb, E., and Steitz, J.A. 1989. Function of the mammalian La protein: evidence for its action in transcrip- 
tion termination by RNA polymerase III. EMBO J 8:851-861. 
Howe, J. G. , and Shu, M.-D. 1989. Epstein-Barr virus small RNA (EBER) genes: unique transcription units that 
combine RNA polymerase II and III promoter elements. Cell 57:825-834. 
Kedes, D.H., and Steitz, J.A. 1988. Correct in vivo splicing of the mouse immunoglobulin k light-chain pre- 
mRNA is dependent on 5' splice-site position even in the absence of transcription. Genes Dev 2:1448- 
1459. 
Continued 
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