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)

Alanine/glyoxylate aminotransferase 1 (AGT) is peroxisomal in most normal humans, but in some patients with the hereditary disease primary hyperoxaluria type 1 (PH1), AGT is mislocalized to the mitochondria. In an attempt to identify the sequences in AGT that mediate its targeting to peroxisomes, and to determine the mechanism by which AGT is mistargeted in PH1, we have studied the intracellular compartmentalization of various normal and mutant AGT polypeptides in normal human fibroblasts and cell lines with selective deficiencies of peroxisomal protein import, using immunofluorescence microscopy after intranuclear microinjection of AGT expression plasmids. The results show that AGT is imported into peroxisomes via the peroxisomal targeting sequence type 1 (PTS1) translocation pathway. Although the COOH-terminal KKL of human AGT was shown to be necessary for its peroxisomal import, this tripeptide was unable to direct the peroxisomal import of the bona fide peroxisomal protein firefly luciferase or the reporter protein bacterial chloramphenicol acetyltransferase. An ill-defined region immediately upstream of the COOH-terminal KKL was also found to be necessary for the peroxisomal import of AGT, but again this region was found to be insufficient to direct the peroxisomal import of chloramphenicol acetyltransferase. Substitution of the COOH-terminal KKL of human AGT by the COOH-terminal tripeptides found in the AGTs of other mammalian species (SQL, NKL), the prototypical PTS1 (SKL), or the glycosomal PTS1 (SSL) also allowed peroxisomal targeting, showing that the allowable PTS1 motif in AGT is considerably more degenerate than, or at least very different from, that acceptable in luciferase. AGT possessing the two amino acid substitutions responsible for its mistargeting in PH1 (i.e., Pro11-->Leu and Gly170-->Arg) was targeted mainly to the mitochondria. However, AGTs possessing each amino acid substitution on its own were targeted normally to the peroxisomes. This suggests that Gly170-->Arg-mediated increased functional efficiency of the otherwise weak mitochondrial targeting sequence (generated by the Pro11-->Leu polymorphism) is not due to interference with the peroxisomal targeting or import of AGT.
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PMID:Mammalian alanine/glyoxylate aminotransferase 1 is imported into peroxisomes via the PTS1 translocation pathway. Increased degeneracy and context specificity of the mammalian PTS1 motif and implications for the peroxisome-to-mitochondrion mistargeting of AGT in primary hyperoxaluria type 1. 755 90

To study structure-function relationships of the growth hormone (GH) receptor (GHR), two functional systems have been developed. CHO cells were transiently cotransfected with the cDNA encoding the full-length rat GHR and with a construct consisting of the 5' flanking region of one of two GH-dependent genes encoding ovine beta-lactoglobulin or serine protease inhibitor 2.1 (Spi 2.1, formerly Spi.1; the corresponding rat gene has recently been redesignated Spin2a) coupled to the bacterial reporter gene encoding chloramphenicol acetyltransferase (CAT). Transfected cells were grown in the absence and presence of human GH and dexamethasone for the Spi 2.1 gene construct. GH was able to activate each promoter (with approximately 4-fold induction of CAT activity) in a dose-dependent manner. For both tests, the maximal effect was observed at 20 nM human GH. These tests have been used to identify functional domains of the GHR. Two truncated (T) GHRs, lacking most or part of the cytoplasmic domain [called T276 (ending at residue 276) and T436 (ending at residue 436)], were unable to stimulate CAT activity. The GHR contains a proline-rich region, called "Box I," conserved in the cytokine/GH/prolactin receptor family. Alanine substitutions for the four prolines of GHR Box I were introduced. Single proline-to-alanine mutations did not affect the functional activity of the GHR. However, modification of the four prolines together or deletion of the Box I (15 amino acids between positions 279 and 293) resulted in the complete absence of GH stimulation. Thus, the proline-rich region, shown to be important for other members of this receptor superfamily, is also critical for GH signal transduction.
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PMID:Cytoplasmic sequences of the growth hormone receptor necessary for signal transduction. 830 73

We have investigated protein-protein interactions among the respiratory syncytial virus (RSV) RNA polymerase subunits using affinity chromatography. Here we demonstrate a novel interaction of P and M2-1 proteins. Phosphorylation of either M2-1 or P appears to be dispensable for this interaction. Internal deletions within P mapped the M2-1-binding domain to a region between residues 100 and 120. Alanine-scanning mutagenesis within this region of P revealed that substitution of any one of the three residues, L101, Y102, and F109, prevented both M2-1 and P binding and expression of an M2-1-dependent luciferase reporter gene. However, these same mutations did not prevent the activity of an M2-1-independent chloramphenicol acetyltransferase minigenome, suggesting that these residues of P specifically affect M2-1-P interaction. On the basis of these observations, it is possible that the interaction between RSV M2-1 and P proteins is important for viral replication.
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PMID:Interaction between human respiratory syncytial virus (RSV) M2-1 and P proteins is required for reconstitution of M2-1-dependent RSV minigenome activity. 1297 Apr 53