Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Glucocorticoid treatment induces programmed cell death (apoptosis) in susceptible T lymphocytes. We have previously isolated and characterized 13 genes induced by agents that cause apoptosis in the murine thymoma cell line, WEHI-7TG. One of these genes, now designated Tcl-30, encodes a 2.4-kb mRNA that is specifically expressed in thymus. Sequence analysis of a full-length cDNA for Tcl-30 reveals a potential open reading frame of 454 amino acids that shares sequence identity to a human placental-specific protein of unknown function, PP11. The putative protein encoded by Tcl-30 also contains a cysteine-rich somatomedin B-like domain found in vitronectin, PP11, and the plasma cell membrane glycoprotein, PC-1. Subpopulations of murine thymocytes sorted on the basis of their expression of the CD4, CD8, and surface heat-stable Ag (HSA) were analyzed by an RNase protection assay to determine the expression of Tcl-30 as a function of T cell development. Tcl-30 was expressed exclusively in the HSA+ T cell populations (CD4-CD8-HSA+; CD4+CD8-HSA+; CD4-CD8+HSA+; and CD4+CD8+HSA+) and not in the HSA- single positive T cell populations (CD4+CD8- or CD4-CD8+) of the thymus or spleen. Therefore, we conclude that Tcl-30 expression is lost during T cell maturation and is absent at the most mature stages of T cell development. The function of Tcl-30 is unknown; however, the CD4+CD8+ double-positive subpopulation expressing Tcl-30 represents thymocytes destined to undergo massive intrathymic cell death. The possibility that Tcl-30 expression may define a population of T lymphocytes that is sensitive to glucocorticoid-mediated apoptosis is discussed.
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PMID:Tcl-30, a new T cell-specific gene expressed in immature glucocorticoid-sensitive thymocytes. 150 80

Human PP11 (placental protein 11) was previously described as a serine protease specifically expressed in the syncytiotrophoblast and in numerous tumor tissues. Several PP11-like proteins were annotated in distantly related organisms, such as worms and mammals, suggesting their involvement in evolutionarily conserved processes. Based on sequence similarity, human PP11 was included in a protein family whose characterized members are XendoU, a Xenopus laevis endoribonuclease involved in small nucleolar RNA processing, and Nsp15, an endoribonuclease essential for coronavirus replication. Here we show that the bacterially expressed human PP11 displays RNA binding capability and cleaves single stranded RNA in a Mn(2+)-dependent manner at uridylates, to produce molecules with 2',3'-cyclic phosphate ends. These features, together with structural and mutagenesis analyses, which identified the potential active site residues, reveal striking parallels to the amphibian XendoU and assign a ribonuclease function to PP11. This newly discovered enzymatic activity places PP11-like proteins in a completely new perspective.
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PMID:The tumor marker human placental protein 11 is an endoribonuclease. 1893 97