Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The nucleotide sequence of the pol-env intergenic region of two isolates of caprine arthritis-encephalitis virus (CAEV) was determined. Two open reading frames (orfs) were identified, designated Q and S by homology with visna virus. CAEV orf S is a single exon encoding a deduced 87-amino acid gene product sharing 36 amino acid identities with the visna trans-acting transcriptional activator (Tat). Ten of these identities comprise a conserved CGCRLCNPGW sequence similar to a cysteine-rich domain essential for trans-activation by human immunodeficiency virus Tat. To determine if transcription promoted by the CAEV long terminal repeat (LTR) could be stimulated in CAEV-infected goat synovial membrane cells, a plasmid (pCAE-CAT) expressing bacterial chloramphenicol acetyltransferase (CAT) under control of the CAEV LTR was transfected into uninfected and infected cells. Sixfold enhancement of CAT activity was observed in infected cells using 100 ng of transfected plasmid. To determine if the pol-env region encodes a gene product which trans-activates the CAEV LTR, goat synovial membrane cells were cotransfected with pCAE-CAT and pRSV-1.9, a plasmid expressing the pol-env region under control of the Rous sarcoma virus LTR. Results indicated that the CAEV genome encodes a tat gene product attributable to orf S.
 ...
PMID:Genetic structure of the pol-env region of the caprine arthritis-encephalitis lentivirus genome. 184 32

The human haptoglobin-related gene (HPR) gene codes for a haptoglobin-related protein (Hpr), a component of trypanosome lytic factor which circulates in plasma in small quantities. Except for the presence of a retrovirus-like element, RTVL-Ia, in intron 1, HPR is 92% identical in sequence to the closely linked human haptoglobin gene (HP) gene coding for haptoglobin. We have explored experimentally in tissue culture and in vivo in mice and in humans the influence of the retroviral-like sequence type Ia (RTVL-Ia) element on HPR expression. Transient expression in HepG2 cells of plasmids carrying the HPR promoter joined by a shortened version of intron 1 to the chloramphenicol acetyltransferase (CAT) vector showed that fragments containing the 5' long terminal repeat (LTR) had no significant effect. In contrast, a gag-pol related part and a pol-env-3'LTR related part of RTVL-Ia decreased expression to 20% and 40% of that in their absence but only when they were in naturally occurring orientation. The latter fragment that contains sequences reminiscent of elements essential for retrovirus viability, such as a splicing acceptor site, TATA box and polyA addition signal sequence, was further tested in site-specific transgenic mice. Similar to in vitro experiment, insertion of this fragment into an HPR transgene in mice reduced HPR expression to 50% compared to a transgene without the insert, but none of the viral sequence motifs appear to explain this effect. Instead, we found within the fragment two cryptic splicing donor sites whose products were present in transgenic mouse and in human liver RNA. Our data suggest that a combination of multiple small effects of RTVL-Ia including aberrant splicing accounts for the low (6%) expression of the present-day HPR relative to HP.
 ...
PMID:An intronic endogenous retrovirus-like sequence attenuates human haptoglobin-related gene expression in an orientation-dependent manner. 1459 71