Disease relevance of Tpt1

• p23 is a protein of Ehrlich ascites tumor cells, preferentially synthesized in the exponentially growing tumor [1].
• Polymerase chain reaction, cloning and sequencing of p23 cDNA suggest p23 to be identical with a 21 kDa protein of mouse erythroleukemia cells, the synthesis of which was shown to be controlled also at the translational level (Chitpatima, S. T., Makrides, S., Bandyopadhyay, R., and Brawerman, G. (1988) Nucleic Acids Res. 16, 2350) [1].
• To understand the possible roles of the Tpt1 enzymes as well as the unusual use of NAD, the reaction mechanism of the E. coli homolog KptA was investigated [2].
• The temporal synthesis of the P21 protein of Borrelia burgdorferi and the development of the humoral response to this antigen was assessed in infected mice. p21 is a member of the ospE-F gene family and its protein, P21, has been shown to be expressed by B. burgdorferi within infected mice but not by spirochetes cultured in vitro [3].
• Translationally controlled tumor protein from Madurella mycetomatis, a marker for tumorous mycetoma progression [4].

High impact information on Tpt1

• In the present study, we identify its first immunogenic Ag, a protein homologous to the translationally controlled tumor protein (TCTP), a well-conserved histamine release factor in a range of eukaryotes [4].
• We determined that T cell development was uncoupled from p21 and/or p23 [5].
• Surprisingly, we found, using highly purified proteins, that only Hsp90 and Hsc70 are required for the activation of glucocorticoid receptors in the presence of steroids; in the absence of steroids, either p23 or molybdate are also required as reported previously [6].
• The p24 family member p23 is required for early embryonic development [7].
• In contrast to yeast genetics, in mice disruption of both p23 alleles resulted in early embryonic lethality [7].

Biological context of Tpt1

• We found that mouse Tpt1 is localized on chromosome 14 with a canonical intron-exon organization, a functional promoter, and only one transcript that is ubiquitously expressed in all tissues [8].
• In the present study, seven putative Tpt1 genes with different chromosomal localizations were identified in the mouse genome [8].
• TCTP is implicated in cell growth, acute allergic response, and apoptosis [8].
• The cyclin-dependent kinase inhibitor, p21, is known to be involved in DNA damage-induced cell cycle arrest and blocking DNA replication and repair [9].
• An oligonucleotide affinity column bearing the P7I target site purifies a 21-kDa polypeptide from blastula-stage nuclear extracts, and the amino acid sequence obtained from this polypeptide was used to generate a nucleic acid probe with which the corresponding cDNA was cloned [10].

Anatomical context of Tpt1

• A 21-kDa polypeptide belonging to a new family of proteins is expressed in the Golgi apparatus of neural and germ cells [11].
• These results suggest that the transformation-suppressed cell line R35 is defective in the rate at which it posttranslationally processes ras proteins, possibly because it is slower in polyisoprenylation of the cytoplasmic p23 precursor protein [12].
• The protein synthetic patterns of inflammatory thioglycollate- and proteose peptone-elicited macrophages were strikingly similar, save for the former's greater levels of accumulation of proteins 14 and 28, and the latter's more pronounced expression of p23 [13].
• In order to develop a vaccine against cryptosporidiosis in cattle, we constructed a recombinant bovine herpesvirus-1 (BHV-1) expressing an immunodominant surface protein, p23, of Cryptosporidium parvum sporozoites [14].
• In contrast, p23 mRNA present in poly(A)+RNA isolated from EAT is not translated in cell-free systems of EAT and reticulocytes [15].

Associations of Tpt1 with chemical compounds

• Actinomycin D even results in superinduction of p23 [1].
• The last step of tRNA splicing in yeast is catalyzed by Tpt1 protein, which transfers the 2'-phosphate from ligated tRNA to NAD to produce ADP-ribose 1"-2"-cyclic phosphate (Appr>p) [2].
• Ligand dependence was reconstituted in the presence of molybdate, a transition metal ion known to stabilize the interaction between the molecular chaperone hsp90 and p23 [16].
• Evidence that the co-chaperone p23 regulates ligand responsiveness of the dioxin (Aryl hydrocarbon) receptor [16].
• Following fractionation on sucrose gradients p23 was dissociated from the receptor-hsp90 complex generating a receptor form, which showed ligand-independent release of hsp90 by Arnt and, consequently, ligand-independent activation of the DNA binding activity of the dioxin receptor [16].

Other interactions of Tpt1

• One of these, that codes for a 21-kDa polypeptide, was analyzed with respect to distribution of sites accessible to RNase T1 in the 5'-noncoding region [17].

Analytical, diagnostic and therapeutic context of Tpt1

• Tryptic peptide mapping analysis of the 32P-labeled viral proteins indicated a precursor product relationship between the intracellular phosphorylated, high-molecular-weight peptides and the mature MuMTV phosphoproteins p23 and p27 [18].
• In Western blotting (immunoblotting), intestinal IgA antibodies were shown to react with antigens comigrating with the T. gondii proteins p22, p23, p30, and p43, the 28-kilodalton antigen, and the 55- and 60-kilodalton rhoptry proteins, as recognized by specific monoclonal antibodies [19].
• In MDBK cells infected with the recombinant BHV-1, the antibody against the p23 protein recognized the p23 protein as an approximately 23-kDa specific band in Western blotting analysis [14].

References